121 lines
No EOL
3.4 KiB
C
121 lines
No EOL
3.4 KiB
C
/*
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* Feb 2017, Karl Palsson <karlp@tweak.net.au>
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <libopencm3/stm32/i2c.h>
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#include <libopencm3/stm32/gpio.h>
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#include <libopencm3/stm32/rcc.h>
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#include "trace.h"
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#include "hw.h"
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#include "i2c-master.h"
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#define SENSOR_ADDRESS (0x40)
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enum sht21_cmd_e {
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SHT21_CMD_TEMP_HOLD = 0xe3,
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SHT21_CMD_HUMIDITY_HOLD = 0xe5,
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SHT21_CMD_TEMP_NOHOLD = 0xf3,
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SHT21_CMD_HUMIDITY_NOHOLD = 0xf5,
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SHT21_CMD_WRITE_REG = 0xe6,
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SHT21_CMD_READ_REG = 0xe7,
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SHT21_CMD_RESET = 0xfe,
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/* 0xfa, 0x0f to read serial */
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};
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void i2cm_init(void)
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{
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rcc_periph_clock_enable(hw_details.periph_rcc);
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rcc_periph_reset_pulse(hw_details.periph_rst);
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i2c_set_speed(hw_details.periph, i2c_speed_sm_100k, hw_details.i2c_clock_megahz);
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//i2c_set_speed(hw_details.periph, i2c_speed_fm_400k, hw_details.i2c_clock_megahz);
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i2c_peripheral_enable(hw_details.periph);
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}
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static float sht21_convert_temp(uint16_t raw)
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{
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//assert((raw & 0x2) == 0x2);
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raw &= ~0x3; /* Clear lower status bits */
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float tf = -46.85 + 175.72 * ((float) raw / 65536.0);
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return tf;
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}
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static float sht21_convert_humi(uint16_t raw)
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{
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//assert((raw & 0x2) == 0);
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raw &= ~0x3; /* Clear lower status bits */
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float tf = -6 + 125 * ((float) raw / 65536.0);
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return tf;
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}
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static float sht21_read_temp_hold(uint32_t i2c)
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{
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uint8_t data[3];
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uint8_t cmd = SHT21_CMD_TEMP_HOLD;
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i2c_transfer7(i2c, SENSOR_ADDRESS, &cmd, 1, data, sizeof(data));
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uint8_t crc = data[2];
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uint16_t temp = data[0] << 8 | data[1];
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// TODO - calcualte CRC and check!
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printf("CRC=%#x, data0=%#x, data1=%#x\n", crc, data[0], data[1]);
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return sht21_convert_temp(temp);
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}
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static float sht21_read_humi_hold(uint32_t i2c)
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{
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uint8_t data[3];
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uint8_t cmd = SHT21_CMD_HUMIDITY_HOLD;
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i2c_transfer7(i2c, SENSOR_ADDRESS, &cmd, 1, data, sizeof(data));
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uint8_t crc = data[2];
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uint16_t left = data[0] << 8 | data[1];
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// TODO - calcualte CRC and check!
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printf("CRC=%#x, data0=%#x, data1=%#x\n", crc, data[0], data[1]);
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return sht21_convert_humi(left);
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}
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static void sht21_readid(void)
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{
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uint8_t raw = 0;
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uint8_t cmd = SHT21_CMD_READ_REG;
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printf("RP...");
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i2c_transfer7(hw_details.periph, SENSOR_ADDRESS, &cmd, 1, &raw, 1);
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printf("..S/S\n");
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// or, with stop/start
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i2c_transfer7(hw_details.periph, SENSOR_ADDRESS, &cmd, 1, 0, 0);
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i2c_transfer7(hw_details.periph, SENSOR_ADDRESS, 0, 0, &raw, 1);
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printf("raw user reg = %#x\n", raw);
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int resolution = ((raw & 0x80) >> 6) | (raw & 1);
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printf("temp resolution is in %d bits\n", 14 - resolution);
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printf("battery status: %s\n", (raw & (1 << 6) ? "failing" : "good"));
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printf("On chip heater: %s\n", (raw & 0x2) ? "on" : "off");
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uint8_t req1[] = {0xfa, 0x0f};
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uint8_t res[8];
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i2c_transfer7(hw_details.periph, SENSOR_ADDRESS, req1, sizeof(req1), res, 8);
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uint8_t req2[] = {0xfc, 0xc9};
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uint8_t res2[8];
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i2c_transfer7(hw_details.periph, SENSOR_ADDRESS, req1, sizeof(req1), res2, 8);
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printf("Serial = %02x%02x %02x%02x %02x%02x %02x%02x\n",
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res2[3], res2[4], res[0], res[2], res[4], res[6], res2[0], res2[1]);
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}
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void i2cm_task(void)
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{
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static int i = 1;
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printf(">>>>Starting iteration %d\n", i++);
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gpio_set(hw_details.trigger_port, hw_details.trigger_pin);
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sht21_readid();
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float temp = sht21_read_temp_hold(hw_details.periph);
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float humi = sht21_read_humi_hold(hw_details.periph);
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gpio_clear(hw_details.trigger_port, hw_details.trigger_pin);
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printf("Temp: %f C, RH: %f\n", temp, humi);
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} |