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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 "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(0, 0, 3, 0);
gpio_peripheral(0, 1, 3, 0);
// Set 100Khz frequency
uint32_t PCLK = SystemCoreClock / 4, 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;
}
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);
}
static void
i2c_send(uint8_t *data, int data_len)
{
i2c_init();
uint32_t timeout = timer_read_time() + timer_from_us(5000);
i2c_start(timeout);
while (data_len--)
i2c_send_byte(*data++, timeout);
i2c_stop(timeout);
}
// This provides just enough functionality to program an MCP4451 chip
void
command_i2c_send(uint32_t *args)
{
uint8_t data_len = args[0], *data = (void*)(size_t)args[1];
i2c_send(data, data_len);
}
DECL_COMMAND(command_i2c_send, "i2c_send data=%*s");
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