Memory-mapped I/O ports

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00000000 - Boot1 ROM

On the older hardware model, this is 512kB of NOR flash; on the newer model, it is 128kB of on-chip ROM.

Note: TI's INT_MMU_Initialize function uses the MMU to map the boot1 ROM (physical address 000xxxxx) at virtual address D40xxxxx, and the SRAM (physical address A40xxxxx) at virtual address 000xxxxx.

10000000 - SDRAM

8FFF0000 - SDRAM control

Write-only (reads just return the last word read from SDRAM). In the OS, all code that uses these registers is copied to SRAM and run from there, rather than running it directly from the SDRAM.

90000000 - General Purpose I/O (GPIO)

The GPIO registers are separated into 4 sections:

  • Section 0: 90000000-9000003F
  • Section 1: 90000040-9000007F
  • Section 2: 90000080-900000BF
  • Section 3: 900000C0-900000FF.

Each register is a word, and only bits 0-7 of each are used. There can be up to 32 devices accessed by this setup, each known as a GPIO. Each GPIO is defined by one of the 8 bits in one of the sections. The number of the GPIO is the section number times 8 plus the bit number. Each GPIO has a status bit and can cause interrupts.

The following addresses are offsets from the beginning of the GPIO section:

  • +00 (R): Masked interrupt status ([+04] & [+08])
  • +04 (R): Reads raw interrupt status (directly dependent on the GPIO input) or sticky interrupt status (becomes set when GPIO status changes) depending on bit in [+20]
  • +04 (W): Write 1 to the bit to reset the sticky interrupt status.
  • +08 (R): Reads current interrupt mask bit.
  • +08 (W): Write 1 to the bit to enable interrupt (set mask bit to 1)
  • +0C (W): Write 1 to the bit to disable interrupt (set mask bit to 0)

The following addresses should be changed with a read-modify-write pattern so as to not disturb other bits in the register.

  • +10 (R/W): Direction (set bit to 0 for output, 1 for input)
  • +14 (R/W): GPIO output bit
  • +18 (R): Reads GPIO input bit.
  • +1C (R/W): Setting bit to 1 will invert raw interrupt status (?)
  • +20 (R/W): Setting bit to 1 will use sticky interrupt status in [+04], or setting to 0 will use raw interrupt status.
  • +24 (R/W): (?)

Currently known GPIOs:

  • GPIO 1 (Section 0, bit 1): Touchpad "clock" (non-CX only) (protocol is I²C, see Keypads#Touchpad I²C for details)
  • GPIO 2 (Section 0, bit 2): Input bit is 0 if battery door open, 1 if closed (TI-Nspire CAS)
  • GPIO 3 (Section 0, bit 3): Touchpad data (non-CX only)
  • GPIO 8 (Section 1, bit 0): Input bit is 0 if Reset Button is pressed.
  • GPIO 24 (Section 3, bit 0): Input bit is 1 if a keypad is not plugged in. (TI-Nspire non-CAS only?)

90010000 - Fast timer

The same interface as 900C0000/900D0000, but runs at the speed of the APB clock (22.5MHz) rather than 32kHz. See Second timer for more info.

90020000 - Serial UART

Used to communicate with the RS232 serial port. The register interface is like that of the 16550 UART used in PCs. The following documentation is for classic TI-Nspire. The CX uses a PL011.

The UART clock on the CX runs at approximately 12MHz while the classic TI-Nspires has the same clock rate as the APB. The clocks are used to calculate the divisors for the baud rates. The formula for working out divisors on the classic TI-Nspires is: divisor = clock_rate / (baud_rate * 16). Similarly, the UART clock rate can be deduced by calculating: clock_rate = divisor * (baud_rate * 16). The current divisor can be found by setting bit 7 in the Line Control Register then (*0x90020000) | (*0x90020004)<<8.

  • 90020000 (R): Receiver Buffer Register (if bit 7 is set in the LCR, this reads the LSB of the divisor)
  • 90020000 (W): Transmitter Holding Register (if bit 7 is set in the LCR, this writes the LSB of the divisor)
  • 90020004 (R/W): Interrupt Enable Register (if bit 7 is set in the LCR, this is the MSB of the divisor)
  • 90020008 (R): Interrupt Identification Register
  • 90020008 (W): FIFO Control Register
  • 9002000C (R/W): Line Control Register
  • 90020010 (R/W): Modem Control Register
  • 90020014 (R): Line Status Register
  • 90020018 (R): Modem Status Register
  • 9002001C (R/W): Scratch Register

90030000 - Second UART

Same port structure as 90020000. It is unknown whether this is connected to anything external, and this doesn't seem to generate interrupts.

90050000 - I2C controller

The Touchpad on the CX is accessed through this controller instead of bitbanging the GPIO. See Keypads#Touchpad I²C for details. It seems to be a Synopsys Designware I2C adapter.

  • 90050000 (R/W): Control register?
  • 90050004 (?): ?
  • 90050010 (R/W): Data/command register
  • 90050014 (R/W): Speed divider for high period (standard speed) OS: 0x9c
  • 90050018 (R/W): Speed divider for low period (standard speed) OS: 0xea
  • 9005001c (R/W): Speed divider for high period (high speed) OS: 0x3b
  • 90050020 (R/W): Speed divider for low period (high speed) OS: 0x2b
  • 9005002c (R/W?): Interrupt status
  • 90050030 (R/W): Interrupt mask
  • 90050040 (R/W): Interrupt clear. Write 1 bits to clear
  • 9005006c (R/W): Enable register
  • 90050070 (R): Status register
  • 90050074 (R?/W): TX FIFO?
  • 90050078 (R?/W): RX FIFO?
  • 900500f4 (?): ?
  • 90050080 (?): ?

90060000 - Watchdog timer

Possibly an ARM SP805 or compatible.

90080000 - Unknown

90090000 - Real-Time Clock (RTC)

Similar to the ARM PrimeCell PL031, but interrupt registers are different.

  • 90090000 (R): Current time, increments by 1 every second.
  • 90090004 (R/W): Alarm value. When the time passes this, interrupt becomes active.
  • 90090008 (R/W): Sets the value of 90090000 (clock will not read new time until a couple seconds later). Reads last value written.
  • 9009000C (R/W): Interrupt mask (1-bit)
  • 90090010 (R/W): Masked interrupt status, reads 1 if interrupt active and mask bit is set. Write 1 to acknowledge.
  • 90090014 (R): Status
    • Bit 0: Time setting in progress
    • Bit 1: Alarm setting in progress
    • Bit 2: Interrupt acknowledgment in progress
    • Bit 3: Interrupt mask setting in progress

900A0000 - Miscellaneous

  • 900A0000 (R): ? 0x101 on CX, else 0x01000010.
  • 900A0004 (R/W): Set bit 0x20 to enable TI-84+ keypad link port. Other bits likely control functions of peripherals as well.
  • 900A0008 (W): Write a 2 to cause a hardware reset
  • 900A0010 (R/W): Fast timer interrupt status/acknowledge (6-bit). Write "1" bits to reset the corresponding interrupt requests.
  • 900A0014 (R/W): Fast timer interrupt mask (6-bit). Set bits to 1 if the corresponding bits in [900A0010] should trigger an IRQ.
  • 900A0018 (R/W): Timer 1 interrupt status/acknowledge (6-bit). Write "1" bits to reset the corresponding interrupt requests.
  • 900A001C (R/W): Timer 1 interrupt mask (6-bit). Set bits to 1 if the corresponding bits in [900A0018] should trigger an IRQ.
  • 900A0020 (R/W): Timer 2 interrupt status/acknowledge (6-bit). Write "1" bits to reset the corresponding interrupt requests.
  • 900A0024 (R/W): Timer 2 interrupt mask (6-bit). Set bits to 1 if the corresponding bits in [900A0020] should trigger an IRQ.
  • 900A0028-900A002C (R): These registers together give a 64-bit number (28 is low, 2C is high) which comprises 56 data bits and 8 parity checking bits, allowing any single-bit error in it to be detected and corrected.
    • Parity bit 0: Check of all data bits
    • Parity bits 1, 2, 4, 8, 16, and 32: Checks of the data bits whose positions, expressed in binary, have that respective bit set.
    • Data bits 3, 5-7, 9-15, 17-31, and 33-55: Serial number (middle part of the calculator's Product ID)
    • Data bits 56-57: Unknown
    • Data bits 58-62: "ASIC user flags"; must match the 80E0 field in an OS image. 01 = CAS, 00 = non-CAS, 03 = CM CAS, 02 = CM non-CAS.
    • Parity bit 63: Check of parity bits 1, 2, 4, 8, 16, and 32.
  • 900A0F04 (R/W): Unknown; Boot1 sets this to 0x1D

900B0000 - Power management

900C0000 - First timer

Configured as ~105 Hz timer by the OS (only used in the TI-84+ emulator). Same port structure as Second timer.

900D0000 - Second timer

Two timers are located here, but only the first can generate IRQs. IRQ status/mask is located at [900A0020]. Configured as a ~100 Hz timer by the OS. The TI-Nspire CX timer is a SP804, different than this one.

  • 900D0000 (R/W): Current IRQ timer value (16-bit). Set to 32 by the OS. Increases/decreases each [900D0004] ticks. The value written to this port is saved internally and can be reloaded automatically upon timer completion, depending on settings in [900D0008].
  • 900D0004 (R/W): IRQ timer divider (16-bit). Ticks per count - 1. Set to 9 by the OS. Ticks are 32768Hz.
  • 900D0008 (R/W): IRQ timer control (5-bit).
    • Bit 4: Set to 1 to freeze timer.
    • Bit 3: Set to 1 for increasing timer, or to 0 for decreasing timer.
    • Bits 2-0: If 0, timer will count to zero and stop. If 1-6, timer will complete when it reaches the corresponding timer completion value and then reload with original timer value (see [900D0018] to [900D002C]). If 7, timer will never complete and runs infinitely.
  • 900D000C (R/W): Current timer value (16-bit). Increases/decreases each [900D0010] ticks. The value written to this port is saved internally and can be reloaded automatically upon timer completion, depending on settings in [900D0014].
  • 900D0010 (R/W): Timer divider (16-bit). Ticks per count - 1. Ticks are approximately 32 kHz.
  • 900D0014 (R/W): Timer control (5-bit).
    • Bit 4: Set to 1 to freeze timer, or 0 to run timer.
    • Bit 3: Set to 1 for increasing timer, or to 0 for decreasing timer.
    • Bits 2-0: If 0, timer will count to zero and stop. If 1-6, timer will complete when it reaches the corresponding timer completion value (see [900D0018] to [900D002C]). If 7, timer will not complete and runs infinitely.
  • 900D0018 (R/W): Timer completion value 1 (16-bit). If IRQ timer equals this value, bit 0 of the interrupt status becomes set.
  • 900D001C (R/W): Timer completion value 2 (16-bit). If IRQ timer equals this value, bit 1 of the interrupt status becomes set.
  • 900D0020 (R/W): Timer completion value 3 (16-bit). If IRQ timer equals this value, bit 2 of the interrupt status becomes set.
  • 900D0024 (R/W): Timer completion value 4 (16-bit). If IRQ timer equals this value, bit 3 of the interrupt status becomes set.
  • 900D0028 (R/W): Timer completion value 5 (16-bit). If IRQ timer equals this value, bit 4 of the interrupt status becomes set.
  • 900D002C (R/W): Timer completion value 6 (16-bit). If IRQ timer equals this value, bit 5 of the interrupt status becomes set.
  • 900D0030 (R/W): Unknown 6-bit value.

900E0000 - Keypad controller

See also Keypads for information about the keypads themselves.

  • 900E0000 (R/W):
    • Bits 0-1: Scan mode
      • Mode 0: Idle.
      • Mode 1: Indiscriminate key detection. Data registers are not updated, but whenever any key is pressed, interrupt bit 2 is set (and cannot be cleared until the key is released).
      • Mode 2: Single scan. The keypad is scanned once, and then the mode returns to 0.
      • Mode 3: Continuous scan. When scanning completes, it just starts over again after a delay.
    • Bits 2-15: Number of APB cycles to wait before scanning each row
    • Bits 16-31: Number of APB cycles to wait between scans
  • 900E0004 (R/W):
    • Bits 0-7: Number of rows to read (later rows are not updated in 900E0010-900E002F, and just read as whatever they were before being disabled)
    • Bits 8-15: Number of columns to read (later column bits in a row are set to 1 when it is updated)
  • 900E0008 (R/W): Keypad interrupt status/acknowledge (3-bit). Write "1" bits to acknowledge.
    • Bit 0: Keypad scan complete
    • Bit 1: Keypad data register changed
    • Bit 2: Key pressed in mode 1
  • 900E000C (R/W): Keypad interrupt mask (3-bit). Set each bit to 1 if the corresponding event in [900E0008] should cause an interrupt.
  • 900E0010-900E002F (R): Keypad data, one halfword per row.
  • 900E0030-900E003F (R/W): Keypad GPIOs. Each register is 20 bits, with one bit per GPIO. The role of each register is unknown.
  • 900E0040 (R/W): Interrupt enable. Bits unknown but seems to be related to touchpad. Causes interrupt on touchpad touched.
  • 900E0044 (R/W): Interrupt status. Bits unknown. Write 1s to acknowledge.
  • 900E0048 (R/W): Unknown

900F0000 - HDQ/1-Wire and LCD contrast

The HDQ/1-Wire registers resemble those on the TI OMAP processors, and are possibly used to communicate with the wireless cradle. There is no conceivable reason for the LCD contrast register to be part of the same module, but here it is. :-(

  • 900F0004 (W): Transmitted data
  • 900F0008 (R): Received data
  • 900F000C (R/W): Control/status
  • 900F0010 (R): Interrupt status (automatically acknowledged when read)
  • 900F0020 (R/W): LCD contrast/backlight. Valid range for contrast (classics): 0x6B to 0x95; normal value is 0x80. Valid OS ranges for backlight (CX): 0x11a to 0x1ce; normal value is 0x174. However, the total range for the CX ranges from 0x100 (backlight off) to about 0x1d0 (about max brightness).

90100000 - TI-84 Plus link port

  • 90100000 (W): Write to bits 0-1 to hold I/O link lines low or let them go high. 1=high, 0=low.
  • 90100000 (R): Bits 0-1 hold the status of the I/O link lines. 1=high, 0=low. Bits 4-5 hold the last value outputted to bits 0-1.
  • 90100004 (R/W): Unknown. The OS writes 0x80 here during initialization.
  • 90100008 (R): Unknown. Bit 0x40 is set if any link lines are low.

90110000 - LED

  • 90110B00 (R/W): Control register
    • Bit 0: Set this bit to enable green light blink data. If green blink data iteration is not on, the green light state is read from bit 0 of green blink data.
    • Bit 1: Set this bit and bit 6 to enable green blink data iteration.
    • Bit 2: Set this bit to force green light off. Overrides bit 4.
    • Bit 3: Set this bit to force red light off. Overrides bits 5 and 13.
    • Bit 4: Set this bit to force green light on.
    • Bit 5: Set this bit to force red light on.
    • Bit 6: See this bit and bit 1 to enable green blink data iteration. Reset before modifying green blink data or delay.
    • Bit 9: Set this bit to enable red light blink data. If red blink data iteration is not on, the red light state is read from bit 0 of red blink data.
    • Bit 10: Set this bit and bit 12 to enable red blink data iteration.
    • Bit 12: Set this bit and bit 10 to enable red blink data iteration. Reset before modifying red blink data or delay.
    • Bit 13: Forces red light on if bit 4 is 0, or red light off if bit 4 is 1. (?)
  • 90110B04 (R/W): Green blink data. 32 bits of on and off state, represented by 1 and 0. Iteration is done from bit 31 to bit 0 repeatedly.
  • 90110B08 (R/W): Green blink delay (negative). OS sets this to -2048.
  • 90110B0C (R/W): Red blink data. 32 bits of on and off state, represented by 1 and 0. Iteration is done from bit 31 to bit 0 repeatedly.
  • 90110B10 (R/W): Red blink delay (negative). OS sets this to -2048.

Note: If red and green lights are on at the same time, the color becomes yellow.

A0000000 - Unknown

The OS's page table has an entry to allow this to be accessed, but no known code does so. (In the newer hardware model, this just mirrors the BOOT1 ROM.)

A4000000 - Internal SRAM

A4000100-A40096FF is used by the OS as the LCD screen buffer. The upper left corner is the first byte. Each grayscaled pixel is 4-bit long. 1111 is white, 0000 is black. On CX with colors enabled, each pixel is 16-bit long: 5 bits for red, 6 bits for green, 5 bits for blue. (Note: CX buffer is too large to fit in this memory region and is instead located in SDRAM. It is recommended to read the location of the buffer from C0000010.)

A9000000 - SPI

Possibly used to communicate with the wireless cradle.

  • A9000008 (R/W): Bits 0-3 = clock speed divider - 1
  • A900000C (R/W): Bit 0 = set to 1 to start transfer; bits 16-21 = number of bits to transfer - 1
  • A9000010 (R): Bit 0 set when transfer complete
  • A9000014 (R/W): Unknown
  • A9000018 (R/W): Unknown
  • A900001C (R/W): Data register low
  • A9000020 (R/W): Data register high

AC000000 - SD Host Controller

See http://www.sdcard.org/developers/tech/host_controller/simple_spec/

B0000000 - USB OTG controller

The OTG controller on all models is a ChipIdea-based dual-role USB controller.

On the Clickpad, appears to be Freescale's USB OTG controller revision 0x42. Its documentation can be found in the MCF54455 reference manual which happens to use the same revision of the module. The host interface is based on EHCI 1.0.

  • Module identification registers
    • B0000000 (R): ID - Identification register - default 0x0042FA05
    • B0000004 (R): HWGENERAL - General hardware parameters - default 0x000007C5
    • B0000008 (R): HWHOST - Host hardware parameters - default 0x10020001
    • B000000C (R): HWDEVICE - Device hardware parameters - default 0x00000009
    • B0000010 (R): HWTXBUF - TX buffer hardware parameters - default 0x80040604
    • B0000014 (R): HWRXBUF - RX buffer hardware parameters - default 0x00000404
  • Capability registers
    • B0000100 (R): CAPLENGTH - Capability registers length - default 0x0100
    • B0000102 (R): HCIVERSION - Host controller interface version - default 0x0040
    • B0000104 (R): HCSPARAMS - Host controller structural parameters - default 0x00010011
    • B0000108 (R): HCCPARAMS - Host controller capability parameters - default 0x00000006
    • B0000120 (R): DCIVERSION - Device controller interface version - default 0x00000001
    • B0000124 (R): DCCPARAMS - Device controller capability parameters - default 0x00000184 (host-capable, device-capable, 4 endpoints)
  • Operational registers
    • B0000140 (R/W): USBCMD - USB command - default 0x00080000 (in device mode)
    • B0000144 (R/W): USBSTS - USB status - default 0x00000080
    • B0000148 (R/W): USBINTR - USB interrupt enable - default 0x00000000
    • B000014C (R/W): FRINDEX - USB frame index - default 0x00000000
    • B0000150 (R): CTRLDSSEGMENT - 4G segment selector (always 0?)
    • B0000154 (R/W): (in host mode) PERIODICLISTBASE - Frame list base address
    • B0000154 (R/W): (in device mode) DEVICEADDR - Device address
    • B0000158 (R/W): (in host mode) ASYNCLISTADDR - Current asynchronous list address
    • B0000158 (R/W): (in device mode) EPLISTADDR - Address at endpoint list
    • B000015C (R/W): TTCTRL - TT status and control - default 0x00000000
    • B0000160 (R/W): BURSTSIZE - Programmable DMA burst size - default 0x00000404
    • B0000164 (R/W): TXFILLTUNING - Host TT Xmit pre-buffer packet tuning - default 0x00000000
    • B0000170 (R/W): ULPI_VIEWPORT - ULPI register access - default 0x00000000
    • B0000180 (R): CONFIGFLAG - Configured flag register (always 1?)
    • B0000184 (R/W): PORTSC - Port status and control - default 0xEC000004
    • B00001A4 (R/W): OTGSC - On-The-Go status and control - default 0x00000120
    • B00001A8 (R/W): USBMODE - USB device mode - default 0x00000000
    • B00001AC (R/W): ENDPOINTSETUPSTAT - Endpoint setup status - default 0x00000000
    • B00001B0 (R/W): ENDPTPRIME - Endpoint initialization - default 0x00000000
    • B00001B4 (R/W): ENDPTFLUSH - Endpoint de-initialize - default 0x00000000
    • B00001B8 (R): ENDPTSTATUS - Endpoint status - default 0x00000000
    • B00001BC (R/W): ENDPTCOMPLETE - Endpoint complete - default 0x00000000
    • B00001C0 (R/W): ENDPTCTRL0 - Endpoint control 0 - default 0x00800080
    • B00001C4 (R/W): ENDPTCTRL1 - Endpoint control 1 - default 0x00000000
    • B00001C8 (R/W): ENDPTCTRL2 - Endpoint control 2 - default 0x00000000
    • B00001CC (R/W): ENDPTCTRL3 - Endpoint control 3 - default 0x00000000

On the CX, a different controller, whose documentation can be found in the IMX233 reference manual, is used. The host interface is, again, based on EHCI; but the register defaults are different. The addresses have been adjusted from the ones contained in the IMX233 reference manual.

    • 0xB0000000: HW_USBCTRL_ID - default 0xE241FA05
    • 0xB0000004: HW_USBCTRL_HWGENERAL - default 0x00000015
    • 0xB0000008: HW_USBCTRL_HWHOST - default 0x10020001
    • 0xB000000C: HW_USBCTRL_HWDEVICE - default 0x0000000B
    • 0xB0000010: HW_USBCTRL_HWTXBUF - default 0x40060910
    • 0xB0000014: HW_USBCTRL_HWRXBUF - default 0x00000710
    • 0xB0000100: HW_USBCTRL_CAPLENGTH - default 0x01000040
    • 0xB0000104: HW_USBCTRL_HCSPARAMS - default 0x00010011
    • 0xB0000108: HW_USBCTRL_HCCPARAMS - default 0x00000006
    • 0xB0000120: HW_USBCTRL_DCIVERSION - default 0x00000001
    • 0xB0000124: HW_USBCTRL_DCCPARAMS - default 0x00000185 (host-capable, device-capable, 5 endpoints)
    • 0xB0000140: HW_USBCTRL_USBCMD - default 0x00080B00 in host mode, 0x00080000 in device mode
    • 0xB0000144: HW_USBCTRL_USBSTS - default 0x00001000 in host mode, 0x00000000 in device mode
    • 0xB0000148: HW_USBCTRL_USBINTR - default 0x00000000
    • 0xB000014C: HW_USBCTRL_FRINDEX - default 0x00000000
    • 0xB0000154: (in host mode) HW_USBCTRL_PERIODICLISTBASE - default 0x00000000
    • 0xB0000154: (in device mode) HW_USBCTRL_DEVICEADDR - default 0x00000000
    • 0xB0000158: (in host mode) HW_USBCTRL_ASYNCLISTADDR - default 0x00000000
    • 0xB0000158: (in device mode) HW_USBCTRL_ENDPOINTLISTADDR - default 0x00000000
    • 0xB000015C: HW_USBCTRL_TTCTRL - default 0x00000000
    • 0xB0000160: HW_USBCTRL_BURSTSIZE - default 0x00001010
    • 0xB0000164: HW_USBCTRL_TXFILLTUNING - default 0x000000000
    • 0xB000016C: HW_USBCTRL_IC_USB - default 0x00000000
    • 0xB0000170: HW_USBCTRL_ULPI - default 0x00000000
    • 0xB0000178: HW_USBCTRL_ENDPTNAK - default 0x00000000
    • 0xB000017C: HW_USBCTRL_ENDPTNAKEN - default 0x00000000
    • 0xB0000184: HW_USBCTRL_PORTSC1 - default 0x10000000
    • 0xB00001A4: HW_USBCTRL_OTGSC - default 0x00000120
    • 0xB00001A8: HW_USBCTRL_USBMODE - default 0x00000000
    • 0xB00001AC: HW_USBCTRL_ENDPTSETUPSTAT - default 0x00000000
    • 0xB00001B0: HW_USBCTRL_ENDPTPRIME - default 0x00000000
    • 0xB00001B4: HW_USBCTRL_ENDPTFLUSH - default 0x00000000
    • 0xB00001B8: HW_USBCTRL_ENDPTSTAT - default 0x00000000
    • 0xB00001BC: HW_USBCTRL_ENDPTCOMPLETE - default 0x00000000
    • 0xB00001C0: HW_USBCTRL_ENDPTCTRL0 - default 0x00100010
    • 0xB00001C4: HW_USBCTRL_ENDPTCTRL1 - default 0x00000000
    • 0xB00001C8: HW_USBCTRL_ENDPTCTRL2 - default 0x00000000
    • 0xB00001CC: HW_USBCTRL_ENDPTCTRL3 - default 0x00000000
    • 0xB00001D0: HW_USBCTRL_ENDPTCTRL4 - default 0x00000000

Role switching

During role switching some GPIO output registers are modified.

  • USB-A: GPIO5 for classic, GPIO2 for CX
    • plugged in: HIGH=>LOW
    • removed: LOW=>HIGH
  • USB-B: GPIO6
    • plugged in: HIGH=>LOW
    • removed: LOW=>HIGH

B4000000 - USB HOST controller

Same port structure as B0000000.

B8000000 - NAND Flash

BC000000 - Unknown

C0000000 - LCD controller

Probably an ARM PrimeCell PL110 or something compatible on the classic TI-Nspire. PL111 on TI-Nspire CX. The following documentation is for the PL110.

  • C0000010 (R/W): Frame Base Address. Holds the address to read pixel data from. Set to A4000100 by the OS.
  • C0000018 (R/W): Interrupt mask.
  • C000001C (R/W): LCD Control
    • Bit 0: LCD controller enable.
    • Bits 1-3: LCD bits per pixel.
      • 000 = 1 bpp
      • 001 = 2 bpp
      • 010 = 4 bpp (default setting of OS)
      • 011 = 8 bpp
      • 100 = 16 bpp (holds the literal 16-bit palette value instead of a palette index)
      • 101 = 24 bpp (not applicable to TI-Nspire's STN LCD)
      • 110,111 = reserved
    • Bit 4: Set to 1 if STN LCD is monochrome, or 0 if color. Should be set to 1 on TI-Nspire.
    • Bit 5: Set to 1 if LCD is TFT, or 0 if STN. Should be set to 0 on TI-Nspire.
    • Bit 6: Set to 1 if monochrome STN LCD has a 8-bit interface, or 0 if 4-bit. Should be set to 1 on TI-Nspire.
    • Bit 7: Set to 1 if LCD is dual panel STN, or 0 if single-panel. Should be set to 0 on TI-Nspire.
    • Bit 8: Set to 1 if the palettes are read as BGR, or 0 if RGB. Since monochrome displays use only the R color, it is possible to store a secondary palette in the B color and switch instantly by flipping this bit.
    • Bit 9: Set to 1 if the bytes in each word are to be read as big-endian, or 0 if little-endian. Set to 0 by the OS.
    • Bit 10: Set to 1 if the pixels within each byte are to be read as big-endian, or 0 if little-endian. Only affects 1,2,4 bpp modes. Set to 1 by the OS.
    • Bit 11: LCD power enable.
    • Bits 12-13: Vertical compare interrupt region.
      • 00 = start of vertical synchronization
      • 01 = start of back porch
      • 10 = start of active video
      • 11 = start of front porch
    • Bits 14-15: Reserved.
    • Bit 16: LCD DMA FIFO Watermark Level.
    • Bits 17-31: Reserved.
  • C0000020 (R): Raw interrupt status.
    • Bit 1: FIFO Underflow
    • Bit 2: LCD next address base update. Signifies that a new Frame Base Address value can be loaded for double-buffering.
    • Bit 3: Vertical compare. Set when one of four vertical regions (specified by the LCD Control register) is reached.
    • Bit 4: AHB Master bus error.
  • C0000024 (R): Masked interrupt status.
  • C0000028 (W): Interrupt clear. Write a 1 to each bit to clear.
  • C000002C (R): Address that is currently being read from (approximate)
  • C0000200-C00003FF (R/W): 256-color palette (each entry is a half-word, but this must be written to an entire word at a time)
    • Bits 0-4: Red palette data (bits 1-4 are the grayscale data on the Nspire screen)
    • Bits 5-9: Green palette data (unused on Nspire)
    • Bits 10-14: Blue palette data (bits 11-14 are the grayscale data on the Nspire screen if BGR mode is set)
    • Bit 15: Intensity (unused on Nspire)

C4000000 - Analog-to-Digital Converter (ADC)

Used to check various voltages. Channels 1 ("VBATT"), 2 ("VSYS"), and 4 ("B12") are used to check the battery status; channel 3 is used to determine which keypad is in use.

  • C4000000 (R): Masked interrupt status (4 bits per channel: bits 0-3 are for channel 0, etc)
  • C4000004 (R/W): Raw interrupt status, write 1 bits to acknowledge
  • C4000008 (R/W): Interrupt enable register
  • C4000100-C40001DF: Per-channel registers (channel 0 starts at C4000100, channel 1 at C4000120, etc.)
    • +00 (R/W): Set bit 0 to start measurement; interrupt status bits 0 and 1 will be set when complete and the value will be stored in +10 register. Other commands do exist, including some that write to memory.
    • +04 (R/W): Unknown (28 bits)
    • +08 (R/W): Number of halfwords to write (25 bits)
    • +0C (R/W): Base address (word-aligned)
    • +10 (R): Read measured voltage. Scale for channels 1 and 2 is 155 units = 1 volt; scale for other channels is 310 units = 1 volt
    • +14 (R/W): Speed (10 bits, set to AHB clock speed / 40000)

C8010000 - Triple DES encryption

Implements the Triple DES encryption algorithm.

  • C8010000 (R/W): Right half of block
  • C8010004 (R/W): Left half of block. Writing this causes the block to be encrypted/decrypted.
  • C8010008 (R/W): Right 32 bits of key 1
  • C801000C (R/W):
    • Bits 0-23: Left 24 bits of key 1
    • Bit 30: Set to 0 to encrypt, 1 to decrypt
  • C8010010 (R/W): Right 32 bits of key 2
  • C8010014 (R/W): Left 24 bits of key 2
  • C8010018 (R/W): Right 32 bits of key 3
  • C801001C (R/W): Left 24 bits of key 3

CC000000 - SHA-256 hash generator

Implements the SHA-256 hash algorithm, which is used in cryptographic signatures.

  • CC000000 (R): Busy if bit 0 set
  • CC000000 (W): Write 0x10 and then 0x0 to initialize. Write 0xA to process first block, 0xE to process subsequent blocks
  • CC000008 (R/W): Some sort of bus write-allow register? If a bit is set, it allows R/W access to the registers of the peripheral, if clear, R/O access only. Don't know what it's doing here, but it's here anyway.
  • CC000010-CC00004F (R/W): 512-bit block
  • CC000060-CC00007F (R): 256-bit state

DC000000 - Interrupt controller

See Interrupts. The controller is a PL190 on TI-Nspire CX. The following documentation is for the classic TI-Nspire.

Registers that operate on sets of IRQs are bitmaps, with bit 0 corresponding to IRQ 0, and so on.

  • DC000000 (R): Masked IRQ status (always equal to [DC000004] & [DC000008])
  • DC000004 (R): Raw interrupt status or sticky interrupt status, depending on bitfield in DC000204
  • DC000004 (W): Resets a set of sticky interrupts
  • DC000008 (R): Current set of enabled IRQs
  • DC000008 (W): Enable a set of IRQs
  • DC00000C (R): Mirror of DC000008
  • DC00000C (W): Disable a set of IRQs
  • DC000020 (R): Reads current IRQ number (no side effects)
  • DC000024 (R): Reads current IRQ number, copies the value in DC00002C to DC000028, writes the priority of the current IRQ to DC00002C
  • DC000028 (R): Reading this register will reset the IRQ request. The value read is whatever was last copied by reading DC000024
  • DC00002C (R/W): 4-bit value. IRQs with priority greater than or equal to this value will not be requested
  • DC000100 (R): Masked FIQ status (always equal to [DC000104] & [DC000108])
  • DC000104 (R): Raw interrupt status or sticky interrupt status, depending on bitfield in DC000204
  • DC000104 (W): Resets a set of sticky interrupts
  • DC000108 (R): Current set of enabled FIQs
  • DC000108 (W): Enable a set of FIQs
  • DC00010C (R): Mirror of DC000108
  • DC00010C (W): Disable a set of FIQs
  • DC000120 (R): Reads current FIQ number (no side effects)
  • DC000124 (R): Reads current FIQ number, copies the value in DC00012C to DC000128, writes the priority of the current IRQ to DC00012C
  • DC000128 (R): Reading this register will reset the FIQ request. The value read is whatever was last copied by reading DC000124
  • DC00012C (R/W): 4-bit value. FIQs with priority greater than or equal to this value will not be requested
  • DC000200 (R/W): Bits that are 0 will invert the corresponding raw interrupt status bit. Typically this register should hold 0xFFFFFFFF.
  • DC000204 (R/W): Bits that are 1 will cause the corresponding bit in DC000004 and DC000104 to read the sticky interrupt status. Bits that are 0 will cause the corresponding bit to read the raw interrupt status.
  • DC000208 (R/W): ?
  • DC000300-DC00037F (W): IRQ priority (0-7). One register per IRQ. Lower values indicate higher priority.
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