Difference between revisions of "83Plus:Ports:01"
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=== Write Values === | === Write Values === | ||
* $FF : Reset the keypad. This unselects all groups and resets the keypad state. | * $FF : Reset the keypad. This unselects all groups and resets the keypad state. | ||
| − | * Anything else : Any 0 bit adds the corresponding group to the list of monitored groups. When a key in a monitored group is pressed, the corresponding key bit reads 1. | + | * Anything else : Any 0 bit adds the corresponding group to the list of monitored groups. When a key in a monitored group is pressed, the corresponding key bit reads 0, otherwise it reads 1 (active-low). |
== Comments == | == Comments == | ||
Revision as of 10:01, 5 February 2007
Synopsis
Port Number: 01h
Function: Keyboard Port
This port reads key presses from the keypad. The keypad is divided into a series of groups.
Read Values
- Bits are set according whether corresponding keys from selected groups are pressed. Groups are selected through writing to the port. A pressed key reads a 0 bit. An unpressed key reads a 1 bit. The port reads FF after a reset (write FF).
Write Values
- $FF : Reset the keypad. This unselects all groups and resets the keypad state.
- Anything else : Any 0 bit adds the corresponding group to the list of monitored groups. When a key in a monitored group is pressed, the corresponding key bit reads 0, otherwise it reads 1 (active-low).
Comments
The key map is laid out as follows:
| Group Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Group Mask | FE | FD | FB | F7 | EF | DF | BF | 7F | ||
| Key Bit | (Mask) | |||||||||
| 0 | (FE) | DOWN | ENTER | (-) | . | 0 | GRAPH | |||
| 1 | (FD) | LEFT | + | 3 | 2 | 1 | STO | TRACE | ||
| 2 | (FB) | RIGHT | - | 6 | 5 | 4 | LN | ZOOM | ||
| 3 | (F7) | UP | * | 9 | 8 | 7 | LOG | WIND | ||
| 4 | (EF) | / | ) | ( | , | x2 | Y= | |||
| 5 | (DF) | ^ | TAN | COS | SIN | x-1 | 2nd | |||
| 6 | (BF) | CLEAR | VARS | PRGM | APPS | MATH | MODE | |||
| 7 | (7F) | STAT | X,T,θ,n | ALPHA | DEL |
- Note: Group FB Key FE is NEGATE, not to be confused with SUBTRACT.
- Note: Group DF Key FE would be ON, but the ON key is tested elsewhere (a "special case" key - after all, it is the ON key).
- Note: Group EF Key BF (APPS) is called MATRIX on the TI-83.
Example
ld a, 0FFh ;Reset the keypad. out (1), a ld a, 0FEh ;Select group 0. out (1), a in a, (1) ;Test for keys. and 0FDh ;Test for Left Arrow key by making A 0 if left was pressed. call z, LeftArrowPressed ;If 0 then left was pressed. ld a, 0FFh ;Reset the keypad. out (1), a
