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ergodox-firmware/firmware/keyboard/ergodox/controller/mcp23018.c

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/* ----------------------------------------------------------------------------
* Copyright (c) 2012, 2013 Ben Blazak <benblazak.dev@gmail.com>
* Released under The MIT License (see "doc/licenses/MIT.md")
* Project located at <https://github.com/benblazak/ergodox-firmware>
* ------------------------------------------------------------------------- */
/** description
* MCP23018 (driven by Teensy 2.0 over TWI) specific code, helping to implement
* the "controller" section of '.../firmware/keyboard.h'
*/
#include <stdbool.h>
#include <stdint.h>
#include <util/twi.h>
#include "../../../../firmware/keyboard.h"
#include "../../../../firmware/lib/twi.h"
#include "./mcp23018.h"
// ----------------------------------------------------------------------------
#if OPT__KB__ROWS != 6 || OPT__KB__COLUMNS != 14
#error "Expecting different keyboard dimensions"
#endif
/** macros/(group) pin drive direction/description
* Select which set of pins (rows or columns) will drive (alternate between
* hi-Z and drive low), and which will be inputs (hi-Z)
*
* Members:
* - `OPT__MCP23018__DRIVE_ROWS`
* - `OPT__MCP23018__DRIVE_COLUMNS`
*
*
* Notes:
*
* - You must set exactly one of these variables to `1`, and the other to `0`
*
* - If you are using internal diodes (inside the key switches), set
* `OPT__MCP23018__DRIVE_ROWS` to `1`
*
* - If the diode cathode is towards the square solder pad, set
* `OPT__MCP23018__DRIVE_COLUMNS` to `1`
*
* - If the diode cathode is towards the circular solder pad, set
* `OPT__MCP23018__DRIVE_ROWS` to `1`
*/
#if ( OPT__MCP23018__DRIVE_ROWS && OPT__MCP23018__DRIVE_COLUMNS ) \
|| !( OPT__MCP23018__DRIVE_ROWS || OPT__MCP23018__DRIVE_COLUMNS )
#error "MCP23018 pin drive direction incorrectly set"
#endif
// ----------------------------------------------------------------------------
// register addresses (see "mcp23018.md")
#define IODIRA 0x00 // i/o direction register
#define IODIRB 0x01
#define GPPUA 0x0C // GPIO pull-up resistor register
#define GPPUB 0x0D
#define GPIOA 0x12 // general purpose i/o port register (write modifies OLAT)
#define GPIOB 0x13
#define OLATA 0x14 // output latch register
#define OLATB 0x15
// TWI aliases
#define TWI_ADDR 0b0100000
#define TWI_ADDR_WRITE ( (TWI_ADDR<<1) | TW_WRITE )
#define TWI_ADDR_READ ( (TWI_ADDR<<1) | TW_READ )
// ----------------------------------------------------------------------------
/** functions/mcp23018__init/description
* Initialize the MCP23018
*
* Returns:
* - success: `0`
* - failure: twi status code
*
* Notes:
* - `twi__stop()` must be called *exactly once* for each twi block, the way
* things are currently set up. this may change in the future.
*/
uint8_t mcp23018__init(void) {
uint8_t ret;
// set pin direction
// - unused : input : 1
// - input : input : 1
// - driving : output : 0
twi__start();
ret = twi__send(TWI_ADDR_WRITE);
if (ret) goto out; // make sure we got an ACK
twi__send(IODIRA);
#if OPT__MCP23018__DRIVE_ROWS
twi__send(0b11111111); // IODIRA
twi__send(0b11000000); // IODIRB
#elif OPT__MCP23018__DRIVE_COLUMNS
twi__send(0b10000000); // IODIRA
twi__send(0b11111111); // IODIRB
#endif
twi__stop();
// set pull-up
// - unused : on : 1
// - input : on : 1
// - driving : off : 0
twi__start();
ret = twi__send(TWI_ADDR_WRITE);
if (ret) goto out; // make sure we got an ACK
twi__send(GPPUA);
#if OPT__MCP23018__DRIVE_ROWS
twi__send(0b11111111); // GPPUA
twi__send(0b11000000); // GPPUB
#elif OPT__MCP23018__DRIVE_COLUMNS
twi__send(0b10000000); // GPPUA
twi__send(0b11111111); // GPPUB
#endif
twi__stop();
// set logical value (doesn't matter on inputs)
// - unused : hi-Z : 1
// - input : hi-Z : 1
// - driving : hi-Z : 1
twi__start();
ret = twi__send(TWI_ADDR_WRITE);
if (ret) goto out; // make sure we got an ACK
twi__send(OLATA);
twi__send(0b11111111); //OLATA
twi__send(0b11111111); //OLATB
out:
twi__stop();
return ret;
}
/** functions/mcp23018__update_matrix/description
* Update the MCP23018 (left hand) half of the given matrix
*
* Arguments:
* - `matrix`: A matrix of booleans, indicating whether the key at the given
* matrix location is pressed or released
*
* Returns:
* - success: `0`
* - failure: twi status code
*/
uint8_t mcp23018__update_matrix(bool matrix[OPT__KB__ROWS][OPT__KB__COLUMNS]) {
uint8_t ret, data;
// initialize things, just to make sure
// - it's not appreciably faster to skip this, and it takes care of the
// case when the i/o expander isn't plugged in during the first
// init()
ret = mcp23018__init();
// if there was an error
if (ret) {
// clear our part of the matrix
for (uint8_t row=0; row<=5; row++)
for (uint8_t col=0; col<=6; col++)
matrix[row][col] = 0;
return ret;
}
// update our part of the matrix ..........................................
#if OPT__MCP23018__DRIVE_ROWS
for (uint8_t row=0; row<=5; row++) {
// set active row low : 0
// set other rows hi-Z : 1
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOB);
twi__send( 0xFF & ~(1<<(5-row)) );
twi__stop();
// read column data
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOA);
twi__start();
twi__send(TWI_ADDR_READ);
twi__read(&data);
twi__stop();
// update matrix
for (uint8_t col=0; col<=6; col++) {
matrix[row][col] = !( data & (1<<col) );
}
}
// set all rows hi-Z : 1
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOB);
twi__send(0xFF);
twi__stop();
#elif OPT__MCP23018__DRIVE_COLUMNS
for (uint8_t col=0; col<=6; col++) {
// set active column low : 0
// set other columns hi-Z : 1
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOA);
twi__send( 0xFF & ~(1<<col) );
twi__stop();
// read row data
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOB);
twi__start();
twi__send(TWI_ADDR_READ);
twi__read(&data);
twi__stop();
// update matrix
for (uint8_t row=0; row<=5; row++) {
matrix[row][col] = !( data & (1<<(5-row)) );
}
}
// set all columns hi-Z : 1
twi__start();
twi__send(TWI_ADDR_WRITE);
twi__send(GPIOA);
twi__send(0xFF);
twi__stop();
#endif
// /update our part of the matrix .........................................
return ret; // success
}
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