144 lines
3.6 KiB
C
144 lines
3.6 KiB
C
/* ----------------------------------------------------------------------------
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* ergoDOX controller: MCP23018 specific code
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* ----------------------------------------------------------------------------
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* Copyright (c) 2012 Ben Blazak <benblazak.dev@gmail.com>
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* Released under The MIT License (MIT) (see "license.md")
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* Project located at <https://github.com/benblazak/ergodox-firmware>
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* ------------------------------------------------------------------------- */
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#include <util/twi.h>
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#include "lib/data-types.h"
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#include "lib/twi.h" // `TWI_FREQ` defined in "teensy-2-0.c"
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#include "matrix.h"
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#include "mcp23018--private.h"
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// register addresses (see "mcp23018.md")
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#define IODIRA 0x00 // i/o direction register
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#define IODIRB 0x01
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#define GPPUA 0x0C // GPIO pull-up resistor register
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#define GPPUB 0x0D
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#define GPIOA 0x12 // general purpose i/o port register (write modifies OLAT)
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#define GPIOB 0x13
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#define OLATA 0x14 // output latch register
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#define OLATB 0x15
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// TWI aliases
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#define TWI_ADDR_WRITE ( (MCP23018_TWI_ADDRESS<<1) | TW_WRITE )
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#define TWI_ADDR_READ ( (MCP23018_TWI_ADDRESS<<1) | TW_READ )
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/* returns:
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* - success: 0
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* - failure: twi status code
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*
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* notes:
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* - `twi_stop()` must be called *exactly once* for each twi block, the way
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* things are currently set up. this may change in the future.
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*/
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uint8_t mcp23018_init(void) {
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uint8_t ret;
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// set pin direction
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// - unused : input : 1
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// - row : input : 1
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// - column : output : 0
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twi_start();
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ret = twi_send(TWI_ADDR_WRITE);
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if (ret) goto out; // make sure we got an ACK
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twi_send(IODIRA);
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twi_send(0b11111111); // IODIRA
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twi_send(0b10000000); // IODIRB
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twi_stop();
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// set pull-up
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// - unused : on : 1
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// - rows : on : 1
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// - columns : off : 0
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twi_start();
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ret = twi_send(TWI_ADDR_WRITE);
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if (ret) goto out; // make sure we got an ACK
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twi_send(GPPUA);
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twi_send(0b11111111); // GPPUA
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twi_send(0b10000000); // GPPUB
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twi_stop();
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// set logical value (doesn't matter on inputs)
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// - unused : high (hi-Z) : 1
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// - rows : high (hi-Z) : 1
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// - columns : high (hi-Z) : 1
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twi_start();
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ret = twi_send(TWI_ADDR_WRITE);
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if (ret) goto out; // make sure we got an ACK
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twi_send(OLATA);
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twi_send(0b11111111); //OLATA
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twi_send(0b11111111); //OLATB
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out:
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twi_stop();
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return ret;
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}
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/* returns:
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* - success: 0
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* - failure: twi status code
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*/
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#if KB_ROWS != 12 || KB_COLUMNS != 7
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#error "Expecting different keyboard dimensions"
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#endif
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uint8_t mcp23018_update_matrix(bool matrix[KB_ROWS][KB_COLUMNS]) {
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uint8_t ret, data;
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// initialize things, just to make sure
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// - it's not appreciably faster to skip this, and it takes care of the
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// case when the i/o expander isn't plugged in during the first
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// init()
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ret = mcp23018_init();
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// if there was an error
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if (ret) {
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// clear our part of the matrix
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for (uint8_t row=0x6; row<=0xB; row++)
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for (uint8_t col=0; col<=6; col++)
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matrix[row][col] = 0;
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return ret;
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}
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// update our part of the matrix
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for (uint8_t col=0; col<=6; col++) {
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// set active column low : 0
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// set other columns high (hi-Z) : 1
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twi_start();
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twi_send(TWI_ADDR_WRITE);
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twi_send(OLATB);
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twi_send( 0xFF & ~(1<<col) );
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twi_stop();
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// read row data
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twi_start();
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twi_send(TWI_ADDR_WRITE);
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twi_send(GPIOA);
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twi_start();
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twi_send(TWI_ADDR_READ);
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twi_read(&data);
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twi_stop();
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// update matrix
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for (uint8_t row=0x6; row<=0xB; row++)
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matrix[row][col] = !( data & (1<<(row-6)) );
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}
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// set all columns high (hi-Z) : 1
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twi_start();
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twi_send(TWI_ADDR_WRITE);
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twi_send(GPIOB);
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twi_send(0xFF);
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twi_stop();
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return ret; // success
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}
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