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// I2C functions on lpc176x
//
// Copyright (C) 2018 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "LPC17xx.h" // LPC_I2C1
#include "board/misc.h" // timer_is_before
#include "command.h" // DECL_COMMAND
#include "gpio.h" // i2c_setup
#include "internal.h" // gpio_peripheral
#include "sched.h" // sched_shutdown
// i2c connection status flags
enum {
IF_START = 1<<5, IF_STOP = 1<<4, IF_IRQ = 1<<3, IF_ACK = 1<<2, IF_ENA = 1<<6
};
static void
i2c_init(void)
{
static int have_run_init;
if (have_run_init)
return;
have_run_init = 1;
// Init i2c bus 1 pins
gpio_peripheral(GPIO(0, 0), 3, 0);
gpio_peripheral(GPIO(0, 1), 3, 0);
// Set 100Khz frequency
enable_pclock(PCLK_I2C1);
uint32_t pclk = SystemCoreClock, pulse = pclk / (100000 * 2);
LPC_I2C1->I2SCLL = pulse;
LPC_I2C1->I2SCLH = pulse;
// Enable interface
LPC_I2C1->I2CONCLR = IF_START | IF_IRQ | IF_ACK | IF_ENA;
LPC_I2C1->I2CONSET = IF_ENA;
}
struct i2c_config
i2c_setup(uint32_t bus, uint32_t rate, uint8_t addr)
{
if (bus)
shutdown("Unsupported i2c bus");
i2c_init();
return (struct i2c_config){ .addr=addr<<1 };
}
static void
i2c_wait(uint32_t bit, uint32_t timeout)
{
for (;;) {
uint32_t flags = LPC_I2C1->I2CONSET;
if (flags & bit)
break;
if (!timer_is_before(timer_read_time(), timeout))
shutdown("i2c timeout");
}
}
static void
i2c_start(uint32_t timeout)
{
LPC_I2C1->I2CONCLR = IF_ACK | IF_IRQ | IF_START;
LPC_I2C1->I2CONSET = IF_ACK | IF_START;
i2c_wait(IF_IRQ, timeout);
uint32_t status = LPC_I2C1->I2STAT;
if (status != 0x10 && status != 0x08)
shutdown("Failed to send i2c start");
LPC_I2C1->I2CONCLR = IF_START;
}
static uint32_t
i2c_send_byte(uint8_t b, uint32_t timeout)
{
LPC_I2C1->I2DAT = b;
LPC_I2C1->I2CONCLR = IF_IRQ;
i2c_wait(IF_IRQ, timeout);
return LPC_I2C1->I2STAT;
}
static void
i2c_stop(uint32_t timeout)
{
LPC_I2C1->I2CONSET = IF_STOP;
LPC_I2C1->I2CONCLR = IF_IRQ;
i2c_wait(IF_STOP, timeout);
}
void
i2c_write(struct i2c_config config, uint8_t write_len, uint8_t *write)
{
uint32_t timeout = timer_read_time() + timer_from_us(5000);
i2c_start(timeout);
i2c_send_byte(config.addr, timeout);
while (write_len--)
i2c_send_byte(*write++, timeout);
i2c_stop(timeout);
}
void
i2c_read(struct i2c_config config, uint8_t reg_len, uint8_t *reg
, uint8_t read_len, uint8_t *read)
{
shutdown("i2c_read not supported on lpc176x");
}
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