diff options
Diffstat (limited to 'src/i2c_software.c')
| -rw-r--r-- | src/i2c_software.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/i2c_software.c b/src/i2c_software.c new file mode 100644 index 00000000..ed0efe53 --- /dev/null +++ b/src/i2c_software.c @@ -0,0 +1,181 @@ +// Software I2C emulation +// +// Copyright (C) 2023 Kevin O'Connor <kevin@koconnor.net> +// Copyright (C) 2023 Alan.Ma <tech@biqu3d.com> +// +// This file may be distributed under the terms of the GNU GPLv3 license. + +#include <string.h> // memcpy +#include "board/gpio.h" // gpio_out_setup +#include "board/internal.h" // gpio_peripheral +#include "board/misc.h" // timer_read_time +#include "basecmd.h" // oid_alloc +#include "command.h" // DECL_COMMAND +#include "sched.h" // sched_shutdown +#include "i2ccmds.h" // i2cdev_set_software_bus + +struct i2c_software { + struct gpio_out scl_out, sda_out; + struct gpio_in scl_in, sda_in; + uint8_t addr; + unsigned int ticks; +}; + +void +command_i2c_set_software_bus(uint32_t *args) +{ + struct i2cdev_s *i2c = i2cdev_oid_lookup(args[0]); + struct i2c_software *is = alloc_chunk(sizeof(*is)); + is->ticks = 1000000 / 100 / 2; // 100KHz + is->addr = (args[4] & 0x7f) << 1; // address format shifted + is->scl_in = gpio_in_setup(args[1], 1); + is->scl_out = gpio_out_setup(args[1], 1); + is->sda_in = gpio_in_setup(args[2], 1); + is->sda_out = gpio_out_setup(args[2], 1); + i2cdev_set_software_bus(i2c, is); +} +DECL_COMMAND(command_i2c_set_software_bus, + "i2c_set_software_bus oid=%c scl_pin=%u sda_pin=%u" + " rate=%u address=%u"); + +// The AVR micro-controllers require specialized timing +#if CONFIG_MACH_AVR + +#define i2c_delay(ticks) (void)(ticks) + +#else + +static unsigned int +nsecs_to_ticks(uint32_t ns) +{ + return timer_from_us(ns * 1000) / 1000000; +} + +static void +i2c_delay(unsigned int ticks) { + unsigned int t = timer_read_time() + nsecs_to_ticks(ticks); + while (t > timer_read_time()); +} + +#endif + +static void +i2c_software_send_ack(struct i2c_software *is, const uint8_t ack) +{ + if (ack) { + gpio_in_reset(is->sda_in, 1); + } else { + gpio_out_reset(is->sda_out, 0); + } + i2c_delay(is->ticks); + gpio_in_reset(is->scl_in, 1); + i2c_delay(is->ticks); + gpio_out_reset(is->scl_out, 0); +} + +static uint8_t +i2c_software_read_ack(struct i2c_software *is) +{ + uint8_t nack = 0; + gpio_in_reset(is->sda_in, 1); + i2c_delay(is->ticks); + gpio_in_reset(is->scl_in, 1); + nack = gpio_in_read(is->sda_in); + i2c_delay(is->ticks); + gpio_out_reset(is->scl_out, 0); + gpio_in_reset(is->sda_in, 1); + return nack; +} + +static void +i2c_software_send_byte(struct i2c_software *is, uint8_t b) +{ + for (uint_fast8_t i = 0; i < 8; i++) { + if (b & 0x80) { + gpio_in_reset(is->sda_in, 1); + } else { + gpio_out_reset(is->sda_out, 0); + } + b <<= 1; + i2c_delay(is->ticks); + gpio_in_reset(is->scl_in, 1); + i2c_delay(is->ticks); + gpio_out_reset(is->scl_out, 0); + } + + if (i2c_software_read_ack(is)) { + shutdown("soft_i2c NACK"); + } +} + +static uint8_t +i2c_software_read_byte(struct i2c_software *is, uint8_t remaining) +{ + uint8_t b = 0; + gpio_in_reset(is->sda_in, 1); + for (uint_fast8_t i = 0; i < 8; i++) { + i2c_delay(is->ticks); + gpio_in_reset(is->scl_in, 1); + i2c_delay(is->ticks); + b <<= 1; + b |= gpio_in_read(is->sda_in); + gpio_out_reset(is->scl_out, 0); + } + gpio_in_reset(is->sda_in, 1); + i2c_software_send_ack(is, remaining == 0); + return b; +} + +static void +i2c_software_start(struct i2c_software *is, uint8_t addr) +{ + i2c_delay(is->ticks); + gpio_in_reset(is->sda_in, 1); + gpio_in_reset(is->scl_in, 1); + i2c_delay(is->ticks); + gpio_out_reset(is->sda_out, 0); + i2c_delay(is->ticks); + gpio_out_reset(is->scl_out, 0); + + i2c_software_send_byte(is, addr); +} + +static void +i2c_software_stop(struct i2c_software *is) +{ + gpio_out_reset(is->sda_out, 0); + i2c_delay(is->ticks); + gpio_in_reset(is->scl_in, 1); + i2c_delay(is->ticks); + gpio_in_reset(is->sda_in, 1); +} + +void +i2c_software_write(struct i2c_software *is, uint8_t write_len, uint8_t *write) +{ + i2c_software_start(is, is->addr); + while (write_len--) + i2c_software_send_byte(is, *write++); + i2c_software_stop(is); +} + +void +i2c_software_read(struct i2c_software *is, uint8_t reg_len, uint8_t *reg + , uint8_t read_len, uint8_t *read) +{ + uint8_t addr = is->addr | 0x01; + + if (reg_len) { + // write the register + i2c_software_start(is, is->addr); + while(reg_len--) + i2c_software_send_byte(is, *reg++); + } + // start/re-start and read data + i2c_software_start(is, addr); + while(read_len--) { + *read = i2c_software_read_byte(is, read_len); + read++; + } + i2c_software_stop(is); +} |