Keypads

Key maps

Each bit in the 900E0010-900E001F registers represents a key. If the bit is cleared, the key is being pressed. Only bits 0 to 10 are used in each halfword. The mapping depends on the currently used keypad.

Clickpad keypad map:

offset	bit 0	bit 1	bit 2	bit 3	bit 4	bit 5	bit 6	bit 7	bit 8	bit 9	bit 10
0010	ret	enter	space	(-)	Z	.	Y	0	X	on	theta
0012	,	+	W	3	V	2	U	1	T	e^x	pi
0014	?	-	S	6	R	5	Q	4	P	10^x	EE
0016	:	*	O	9	N	8	M	7	L	x^2	i
0018	"	/	K	tan	J	cos	I	sin	H	^	>
001A	'	cat	G	)	F	(	E	var	D	caps	<
001C	flag	click	C	home	B	menu	A	esc	|	tab
001E	up	u+r	right	r+d	down	d+l	left	l+u	clear	ctrl	=

TI-84+ keypad map:

offset	bit 0	bit 1	bit 2	bit 3	bit 4	bit 5	bit 6	bit 7	bit 8	bit 9	bit 10
0010	down	left	right	up
0012	enter	+	-	*	/	^	clear
0014	(-)	3	6	9	)	tan	vars
0016	.	2	5	8	(	cos	prgm	stat
0018	0	1	4	7	,	sin	apps	X
001A	on	sto	ln	log	x^2	x^-1	math	alpha
001C	graph	trace	zoom	wind	y=	2nd	mode	del
001E

Touchpad keypad map:

offset	bit 0	bit 1	bit 2	bit 3	bit 4	bit 5	bit 6	bit 7	bit 8	bit 9	bit 10
0010	ret	enter		(-)	space	Z	Y	0	?!
0012	X	W	V	3	U	T	S	1	pi	trig	10^x
0014	R	Q	P	6	O	N	M	4	EE	x^2
0016	L	K	J	9	I	H	G	7	/	e^x
0018	F	E	D		C	B	A	=	*	^
001A		var	-	)	.	(	5	cat	frac	del	scratch
001C	flag		+	doc	2	menu	8	esc		tab
001E									shift	ctrl	,

Touchpad I²C

Communication with the actual touchpad is done with the I²C protocol: GPIO 1 is the Serial Clock (SCL) and GPIO 3 is the Serial Data Line (SDA). The touchpad responds to messages with address 0x20. A write message consists of the first port to write to, followed by the values to write: the port number auto-increments, so a message of 00 de ad writes de to port 00 and ad to port 01. A read message reads from whatever port was set by the previous write message, so it generally has to be preceded by an empty write to set the port.

A list of the touchpad's ports follows. All 16-bit numbers are big-endian.

• Any page:
  • FF: Page number
• Page 04 (default):
  • 00: Contact (usually is 01 if proximity >= 0x2F, 00 otherwise)
  • 01: Proximity
  • 02-03: X position
  • 04-05: Y position
  • 06: X velocity
  • 07: Y velocity
  • 0A: 1 if touchpad pressed down, 0 if not
  • 0B: Status (reading this clears the low bits)
    • Bit 0 (0x01): Set when proximity is nonzero
    • Bit 1 (0x02): Set when velocity bytes are nonzero
    • Bit 2 (0x04): Set when unknown byte at 08 is nonzero
    • Bit 3 (0x08): Set when pressed byte has changed
    • Bit 6 (0x40): Always set? (If it's not set, the OS's interrupt handler overflows the stack and crashes)
  • E4-E7: Firmware version
• Page 10:
  • 04-05: Maximum X coordinate (0x0918)
  • 06-07: Maximum Y coordinate (0x069B)

Keypad Connector

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