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/*
* Feb 2017, Karl Palsson <karlp@tweak.net.au>
*/
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <libopencm3/stm32/i2c.h>
#include <libopencm3/stm32/rcc.h>
#include "trace.h"
#include "hw.h"
#include "i2c-master.h"
#define SENSOR_ADDRESS (0x40)
enum sht21_cmd_e {
SHT21_CMD_TEMP_HOLD = 0xe3,
SHT21_CMD_HUMIDITY_HOLD = 0xe5,
SHT21_CMD_TEMP_NOHOLD = 0xf3,
SHT21_CMD_HUMIDITY_NOHOLD = 0xf5,
SHT21_CMD_WRITE_REG = 0xe6,
SHT21_CMD_READ_REG = 0xe7,
SHT21_CMD_RESET = 0xfe,
/* 0xfa, 0x0f to read serial */
};
void i2cm_init(void)
{
rcc_periph_clock_enable(hw_details.periph_rcc);
rcc_periph_reset_pulse(hw_details.periph_rst);
i2c_set_standard_mode(hw_details.periph);
// i2c_enable_ack(hw_details.periph); /* NO ACK FOR SHT21! */
//i2c_set_dutycycle(hw_details.periph, I2C_CCR_DUTY_DIV2); /* default, no need to do this really */
/* --------- board specific settings! */
i2c_set_clock_frequency(hw_details.periph, I2C_CR2_FREQ_42MHZ);
/* 42MHz / (100kHz * 2) */
i2c_set_ccr(hw_details.periph, 210);
/* standard mode, freqMhz+1*/
i2c_set_trise(hw_details.periph, 43);
/* --------- end of board specific settings!*/
i2c_peripheral_enable(hw_details.periph);
}
static void sht21_send_data(uint32_t i2c, size_t n, uint8_t *data)
{
while ((I2C_SR2(i2c) & I2C_SR2_BUSY)) {
}
i2c_send_start(i2c);
/* Wait for master mode selected */
while (!((I2C_SR1(i2c) & I2C_SR1_SB)
& (I2C_SR2(i2c) & (I2C_SR2_MSL | I2C_SR2_BUSY))));
i2c_send_7bit_address(i2c, SENSOR_ADDRESS, I2C_WRITE);
/* Waiting for address is transferred. */
while (!(I2C_SR1(i2c) & I2C_SR1_ADDR));
/* Cleaning ADDR condition sequence. */
uint32_t reg32 = I2C_SR2(i2c);
(void) reg32; /* unused */
size_t i;
for (i = 0; i < n; i++) {
i2c_send_data(i2c, data[i]);
while (!(I2C_SR1(i2c) & (I2C_SR1_BTF)));
}
}
static void sht21_send_cmd(uint32_t i2c, uint8_t cmd)
{
while ((I2C_SR2(i2c) & I2C_SR2_BUSY)) {
}
i2c_send_start(i2c);
/* Wait for master mode selected */
while (!((I2C_SR1(i2c) & I2C_SR1_SB)
& (I2C_SR2(i2c) & (I2C_SR2_MSL | I2C_SR2_BUSY))));
i2c_send_7bit_address(i2c, SENSOR_ADDRESS, I2C_WRITE);
/* Waiting for address is transferred. */
while (!(I2C_SR1(i2c) & I2C_SR1_ADDR));
/* Cleaning ADDR condition sequence. */
uint32_t reg32 = I2C_SR2(i2c);
(void) reg32; /* unused */
i2c_send_data(i2c, cmd);
while (!(I2C_SR1(i2c) & (I2C_SR1_BTF)));
}
static void sht21_readn(uint32_t i2c, int n, uint8_t *res)
{
//assert(n > 0);
i2c_send_start(i2c);
i2c_enable_ack(i2c);
/* Wait for master mode selected */
while (!((I2C_SR1(i2c) & I2C_SR1_SB)
& (I2C_SR2(i2c) & (I2C_SR2_MSL | I2C_SR2_BUSY))));
i2c_send_7bit_address(i2c, SENSOR_ADDRESS, I2C_READ);
/* Waiting for address is transferred. */
while (!(I2C_SR1(i2c) & I2C_SR1_ADDR));
/* Cleaning ADDR condition sequence. */
uint32_t reg32 = I2C_SR2(i2c);
(void) reg32; /* unused */
int i = 0;
for (i = 0; i < n; ++i) {
if (i == n - 1) {
i2c_disable_ack(i2c);
}
while (!(I2C_SR1(i2c) & I2C_SR1_RxNE));
res[i] = i2c_get_data(i2c);
}
i2c_send_stop(i2c);
return;
}
static float sht21_convert_temp(uint16_t raw)
{
//assert((raw & 0x2) == 0x2);
raw &= ~0x3; /* Clear lower status bits */
float tf = -46.85 + 175.72 * ((float) raw / 65536.0);
return tf;
}
static float sht21_convert_humi(uint16_t raw)
{
//assert((raw & 0x2) == 0);
raw &= ~0x3; /* Clear lower status bits */
float tf = -6 + 125 * ((float) raw / 65536.0);
return tf;
}
static float sht21_read_temp_hold(uint32_t i2c)
{
// gpio_set(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
sht21_send_cmd(i2c, SHT21_CMD_TEMP_HOLD);
uint8_t data[3];
sht21_readn(i2c, 2, data);
uint8_t crc = data[2];
uint16_t temp = data[0] << 8 | data[1];
printf("CRC=%#x, data0=%#x, data1=%#x\n", crc, data[0], data[1]);
// gpio_clear(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
return sht21_convert_temp(temp);
}
static float sht21_read_humi_hold(uint32_t i2c)
{
// gpio_set(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
sht21_send_cmd(i2c, SHT21_CMD_HUMIDITY_HOLD);
uint8_t data[3];
sht21_readn(i2c, 2, data);
uint8_t crc = data[2];
uint16_t left = data[0] << 8 | data[1];
printf("CRC=%#x, data0=%#x, data1=%#x\n", crc, data[0], data[1]);
// gpio_clear(LED_DISCO_BLUE_PORT, LED_DISCO_BLUE_PIN);
return sht21_convert_humi(left);
}
static void sht21_readid(void)
{
sht21_send_cmd(I2C1, SHT21_CMD_READ_REG);
uint8_t raw;
sht21_readn(I2C1, 1, &raw);
printf("raw user reg = %#x\n", raw);
int resolution = ((raw & 0x80) >> 6) | (raw & 1);
printf("temp resolution is in %d bits\n", 14 - resolution);
printf("battery status: %s\n", (raw & (1 << 6) ? "failing" : "good"));
printf("On chip heater: %s\n", (raw & 0x2) ? "on" : "off");
uint8_t req1[] = {0xfa, 0x0f};
uint8_t res[8];
sht21_send_data(I2C1, 2, req1);
sht21_readn(I2C1, sizeof(res), res);
uint8_t req2[] = {0xfc, 0xc9};
uint8_t res2[8];
sht21_send_data(I2C1, 2, req2);
sht21_readn(I2C1, sizeof(res), res2);
printf("Serial = %02x%02x %02x%02x %02x%02x %02x%02x\n",
res2[3], res2[4], res[0], res[2], res[4], res[6], res2[0], res2[1]);
}
void i2cm_task(void)
{
sht21_readid();
float temp = sht21_read_temp_hold(I2C1);
float humi = sht21_read_humi_hold(I2C1);
printf("Temp: %f C, RH: %f\n", temp, humi);
}
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