Sets transmitting power to +8dB

code/b-parasite/config/prst_config.h

@@ -26,6 +26,8 @@
 // Interval between advertising packets.
 // From the specs, this value has to be greater or equal 20ms.
 #define PRST_BLE_ADV_INTERVAL_IN_MS 30
+// Possible values are ..., -8, -4, 0, 4, 8.
+#define PRST_BLE_ADV_TX_POWER 8
 
 // PWM.
 #define PRST_PWM_PIN NRF_GPIO_PIN_MAP(0, 5)

code/b-parasite/src/main.c

@@ -1,20 +1,12 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "app_timer.h"
-#include "ble_advdata.h"
-#include "bsp.h"
-#include "nordic_common.h"
 #include "nrf_delay.h"
-#include "nrf_drv_rtc.h"
 #include "nrf_gpio.h"
 #include "nrf_log.h"
 #include "nrf_log_ctrl.h"
 #include "nrf_log_default_backends.h"
 #include "nrf_pwr_mgmt.h"
-#include "nrf_sdh.h"
-#include "nrf_sdh_ble.h"
-#include "nrf_soc.h"
 #include "prst/adc.h"
 #include "prst/ble.h"
 #include "prst/pwm.h"
@@ -22,34 +14,30 @@
 #include "prst/shtc3.h"
 #include "prst_config.h"
 
-// #define DEAD_BEEF 0xDEADBEEF
-// void assert_nrf_callback(uint16_t line_num, const uint8_t *p_file_name) {
-//   app_error_handler(DEAD_BEEF, line_num, p_file_name);
-// }
-
 // A small wrap-around counter for deduplicating BLE packets on the receiver.
 static uint8_t run_counter = 0;
 
 static void log_init(void) {
-  ret_code_t err_code = NRF_LOG_INIT(NULL);
-  APP_ERROR_CHECK(err_code);
+  APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
   NRF_LOG_DEFAULT_BACKENDS_INIT();
-  NRF_LOG_INFO("Log inited");
+  NRF_LOG_INFO("Log inited.");
 }
 
-static void leds_init(void) {
+static void gpio_init(void) {
   nrf_gpio_cfg_output(PRST_LED_PIN);
-  NRF_LOG_INFO("Leds inited");
+  nrf_gpio_cfg_output(PRST_FAST_DISCH_PIN);
+  NRF_LOG_INFO("GPIO pins inited.");
 }
 
-#define FPU_EXCEPTION_MASK 0x0000009F
-
 static void power_management_init(void) {
-  ret_code_t err_code;
-  err_code = nrf_pwr_mgmt_init();
-  APP_ERROR_CHECK(err_code);
+  APP_ERROR_CHECK(nrf_pwr_mgmt_init());
+  NRF_LOG_INFO("GPIO pins inited.");
 }
 
+// This FPU exception mask trick is recommended for avoiding unwanted
+// interupts from the floating point unit. This would be pretty bad,
+// since it would wake us up from deep sleep for nothing.
+#define FPU_EXCEPTION_MASK 0x0000009F
 static void power_manage(void) {
   __set_FPSCR(__get_FPSCR() & ~(FPU_EXCEPTION_MASK));
   (void)__get_FPSCR();
@@ -57,8 +45,13 @@ static void power_manage(void) {
   nrf_pwr_mgmt_run();
 }
 
-// Here we need to be extra careful with what operations we do. This callback
-// has to return fast-ish, otherwise we hit some hard exceptions.
+// This is the RTC callback in which we do all of our work as quickly as
+// possible:
+// - Measure the soil moisture;
+// - Measure the air temperature and humidity;
+// - Encode the measurements into the BLE advertisement packet;
+// - Turn on BLE advertising for a while;
+// - Turn everything off and return back to sleep.
 static void rtc_callback() {
   nrf_gpio_pin_set(PRST_LED_PIN);
   prst_shtc3_read_t temp_humi = prst_shtc3_read();
@@ -71,7 +64,6 @@ static void rtc_callback() {
   nrf_gpio_pin_clear(PRST_FAST_DISCH_PIN);
   prst_ble_update_adv_data(batt_read.millivolts, temp_humi.temp_millicelcius,
                            temp_humi.humidity, soil_read.relative, run_counter);
-  NRF_LOG_FLUSH();
   prst_adv_start();
   nrf_delay_ms(PRST_BLE_ADV_TIME_IN_MS);
   prst_adv_stop();
@@ -82,8 +74,7 @@ static void rtc_callback() {
 
 int main(void) {
   log_init();
-  nrf_gpio_cfg_output(PRST_FAST_DISCH_PIN);
-  leds_init();
+  gpio_init();
   power_management_init();
   prst_ble_init();
   prst_adc_init();

code/b-parasite/src/prst/adc.c

@@ -11,7 +11,6 @@
 // 10 bits resoltuion.
 #define PRST_ADC_RESOLUTION 10
 
-// #define PRST_ADC_BATT_INPUT NRF_SAADC_INPUT_VDD
 #define PRST_ADC_BATT_INPUT NRF_SAADC_INPUT_VDD
 #define PRST_ADC_BATT_CHANNEL 0
 

code/b-parasite/src/prst/adc.h

@@ -8,7 +8,7 @@
 // I previously did a hacky linear regression to estimate them, but I'm
 // not super sure how useful that is.
 #define PRST_SOIL_WET 200
-#define PRST_SOIL_DRY 500
+#define PRST_SOIL_DRY 450
 
 typedef struct prst_adc_batt_val {
   int16_t raw;

code/b-parasite/src/prst/ble.c

@@ -152,9 +152,9 @@ void prst_ble_update_adv_data(uint16_t batt_millivolts,
 }
 
 void prst_adv_start() {
-  ret_code_t err_code;
-  err_code = sd_ble_gap_adv_start(adv_handle_, PRST_CONN_CFG_TAG);
-  APP_ERROR_CHECK(err_code);
+  APP_ERROR_CHECK(sd_ble_gap_adv_start(adv_handle_, PRST_CONN_CFG_TAG));
+  APP_ERROR_CHECK(sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV,
+                                          adv_handle_, PRST_BLE_ADV_TX_POWER));
 #if PRST_BLE_DEBUG
   NRF_LOG_INFO("[ble] Advertising started.\n");
 #endif

code/b-parasite/src/prst/shtc3.c

@@ -34,8 +34,14 @@ prst_shtc3_read_t prst_shtc3_read() {
   // Wake the sensor up.
   write_cmd(PRST_SHTC3_CMD_WAKEUP);
   nrf_delay_ms(1);
+
   // Request measurement.
-  write_cmd(PRST_SHTC3_CMD_MEASURE_TFIRST_LOW_POWER);
+  write_cmd(PRST_SHTC3_CMD_MEASURE_TFIRST_NORMAL);
+
+  // Reading in normal (not low power) mode can take up to 12.1 ms, according to
+  // the datasheet.
+  nrf_delay_ms(15);
+
   // Read temp and humidity.
   while (nrf_drv_twi_rx(&twi_, PRST_SHTC3_ADDR, buff, 6) != 0) {
     nrf_delay_ms(10);

code/b-parasite/src/prst/shtc3.h

@@ -11,6 +11,7 @@
 #define PRST_SHTC3_CMD_SLEEP 0xb098
 #define PRST_SHTC3_CMD_WAKEUP 0x3517
 #define PRST_SHTC3_CMD_MEASURE_TFIRST_LOW_POWER 0x609c
+#define PRST_SHTC3_CMD_MEASURE_TFIRST_NORMAL 0x7866
 
 typedef struct prst_shtc3_values {
   // Temperature in millicelcius. To get the temp in Celcius, divide this by

data/adc-moisture-estimation/dry.csv

@@ -0,0 +1,67 @@
+input_voltage,adc_output
+2.05,400
+2.05,401
+2.18,410
+2.18,409
+2.18,409
+2.19,410
+2.19,410
+2.24,413
+2.25,413
+2.24,413
+2.33,418
+2.34,418
+2.36,418
+2.38,420
+2.41,423
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+2.41,422
+2.42,421
+2.41,421
+2.41,421
+2.42,423
+2.45,423
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+2.53,427
+2.54,428
+2.56,428
+2.61,431
+2.65,434
+2.66,434
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+2.83,439
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+2.92,442
+2.94,444
+2.94,443
+2.98,445
+3.01,446
+3.03,447
+3.04,448
+3.07,447
+3.11,449
+3.12,450
+3.12,449
+3.15,450
+3.16,451
+3.18,452
+3.20,451
+3.22,453
+3.24,454
+3.25,453
+3.27,455
+3.29,455
+3.30,455
+3.32,456
+3.31,455
+3.31,456
+3.34,456
+3.43,459
+3.46,460
+3.51,460

data/adc-moisture-estimation/wet.csv

@@ -0,0 +1,43 @@
+input_voltage,adc_output
+2.18,225
+2.19,227
+2.20,230
+2.22,230
+2.21,234
+2.22,237
+2.25,235
+2.29,236
+2.35,234
+2.36,234
+2.43,239
+2.45,242
+2.45,241
+2.49,239
+2.53,238
+2.58,238
+2.64,241
+2.64,242
+2.72,247
+2.74,250
+2.78,251
+2.82,252
+2.90,252
+2.95,252
+2.96,250
+3.01,253
+3.06,257
+3.09,261
+3.11,261
+3.18,260
+3.20,260
+3.24,259
+3.26,260
+3.28,261
+3.32,265
+3.38,266
+3.39,268
+3.40,267
+3.45,265
+3.46,263
+3.49,262
+3.51,264