add timer for inter-messsage silence to improve response rate
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@ -16,7 +16,7 @@
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* @file sensor_pzem.c
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2016
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* @note peripherals used: USART @ref sensor_pzem_usart
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* @note peripherals used: USART @ref sensor_pzem_usart, timer @ref sensor_pzem_timer
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*/
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/* standard libraries */
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@ -24,12 +24,14 @@
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#include <stdlib.h> // general utilities
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/* STM32 (including CM3) libraries */
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencm3/stm32/rcc.h> // real-time control clock library
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#include <libopencm3/stm32/gpio.h> // general purpose input output library
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#include <libopencm3/stm32/usart.h> // universal synchronous asynchronous receiver transmitter library
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#include <libopencm3/cm3/nvic.h> // interrupt handler
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#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
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#include <libopencm3/stm32/timer.h> // timer utilities
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/* own libraries */
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#include "sensor_pzem.h" // PZEM electricity meter header and definitions
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#include "global.h" // common methods
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@ -39,6 +41,12 @@
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#define SENSOR_PZEM_USART 2 /**< USART peripheral */
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/** @} */
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/** @defgroup sensor_pzem_timer timer peripheral used for waiting before sending the next request
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* @{
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*/
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#define SENSOR_PZEM_TIMER 2 /**< timer peripheral */
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/** @} */
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/* input and output ring buffer, indexes, and available memory */
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static uint8_t rx_buffer[7] = {0}; /**< buffer for received response */
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static volatile uint8_t rx_i = 0; /**< current position of read received data */
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@ -69,15 +77,26 @@ void sensor_pzem_setup(void)
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usart_enable_rx_interrupt(USART(SENSOR_PZEM_USART)); // enable receive interrupt
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usart_enable(USART(SENSOR_PZEM_USART)); // enable USART
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// setup timer to wait for minimal time before next transmission (after previous transmission or reception)
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rcc_periph_clock_enable(RCC_TIM(SENSOR_PZEM_TIMER)); // enable clock for timer block
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timer_reset(TIM(SENSOR_PZEM_TIMER)); // reset timer state
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timer_set_mode(TIM(SENSOR_PZEM_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock,edge alignment (simple count), and count up
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timer_one_shot_mode(TIM(SENSOR_PZEM_TIMER)); // stop counter after update event (we only need to count down once)
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timer_set_prescaler(TIM(SENSOR_PZEM_TIMER), 550-1); // set the prescaler so this 16 bits timer allows to wait for maximum 500 ms ( 1/(72E6/550/(2**16))=500.62ms )
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timer_set_period(TIM(SENSOR_PZEM_TIMER), 0xffff/2); // the timing is not defined in the specification. I tested until the communication was reliable (all requests get an response)
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timer_clear_flag(TIM(SENSOR_PZEM_TIMER), TIM_SR_UIF); // clear flag
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timer_enable_irq(TIM(SENSOR_PZEM_TIMER), TIM_DIER_UIE); // enable update interrupt for timer
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nvic_enable_irq(NVIC_TIM_IRQ(SENSOR_PZEM_TIMER)); // catch interrupt in service routine
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/* reset buffer states */
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tx_i = 0;
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tx_i = LENGTH(tx_buffer);
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rx_i = 0;
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sensor_pzem_measurement_received = false;
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}
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void sensor_pzem_measurement_request(uint32_t address, enum sensor_pzem_measurement_type_t type)
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{
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if (tx_i!=0) { // transmission is ongoing
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if (tx_i<LENGTH(tx_buffer)) { // transmission is ongoing
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return;
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}
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if (type>=SENSOR_PZEM_MAX) { // invalid type
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@ -93,16 +112,24 @@ void sensor_pzem_measurement_request(uint32_t address, enum sensor_pzem_measurem
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for (uint8_t i=0; i<LENGTH(tx_buffer)-1; i++) {
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tx_buffer[6] += tx_buffer[i]; // calculate buffer
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}
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tx_i = 0; // remember we have a message to send
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usart_enable_tx_interrupt(USART(SENSOR_PZEM_USART)); // enable interrupt to send other bytes
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usart_send(USART(SENSOR_PZEM_USART),tx_buffer[tx_i++]); // start transmission
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if (TIM_CR1(TIM(SENSOR_PZEM_TIMER))&TIM_CR1_CEN) { // timer is already running
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// at the end of the timer the transmission will start automatically
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} else { // no timer is running
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usart_enable_tx_interrupt(USART(SENSOR_PZEM_USART)); // enable interrupt to start sending bytes
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//usart_send(USART(SENSOR_PZEM_USART),tx_buffer[tx_i++]); // start transmission
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}
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sensor_pzem_measurement_received = false; // reset flag
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rx_i = 0; // prepare buffer to receive next measurement
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}
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struct sensor_pzem_measurement_t sensor_pzem_measurement_decode(void)
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{
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struct sensor_pzem_measurement_t measurement; // decoded measurement to return
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measurement.valid = false; // wait until the end to ensure validity
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if (!sensor_pzem_measurement_received) { // no measurement received
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if (rx_i<LENGTH(rx_buffer)) { // buffer is not full, thus no measurement received
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return measurement;
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}
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if ((rx_buffer[0]&0xf0)!=0xa0) { // not a response received
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@ -125,7 +152,7 @@ struct sensor_pzem_measurement_t sensor_pzem_measurement_decode(void)
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measurement.value.voltage = ((uint16_t)rx_buffer[1]<<8)+rx_buffer[2]+rx_buffer[3]*0.1;
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break;
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case SENSOR_PZEM_CURRENT:
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measurement.value.current = rx_buffer[2]+rx_buffer[3]/100;
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measurement.value.current = rx_buffer[2]+rx_buffer[3]*0.01;
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break;
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case SENSOR_PZEM_POWER:
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measurement.value.power = ((uint16_t)rx_buffer[1]<<8)+rx_buffer[2];
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@ -154,7 +181,9 @@ void USART_ISR(SENSOR_PZEM_USART)(void)
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usart_send(USART(SENSOR_PZEM_USART),tx_buffer[tx_i++]); // transmit next byte
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} else { // request transmitted
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usart_disable_tx_interrupt(USART(SENSOR_PZEM_USART)); // disable transmit interrupt
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tx_i = 0; // ready for next transmission
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timer_set_counter(TIM(SENSOR_PZEM_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_PZEM_TIMER)); // start timer between requests
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}
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}
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if (usart_get_interrupt_source(USART(SENSOR_PZEM_USART), USART_SR_RXNE)) { // data has been received
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@ -166,5 +195,20 @@ void USART_ISR(SENSOR_PZEM_USART)(void)
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} else { // previous response not read before receiving the next
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usart_recv(USART(SENSOR_PZEM_USART)); // drop received buffer
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}
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timer_set_counter(TIM(SENSOR_PZEM_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_PZEM_TIMER)); // start timer between requests
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}
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}
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/** interrupt service routine called on timeout */
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void TIM_ISR(SENSOR_PZEM_TIMER)(void)
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{
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if (timer_get_flag(TIM(SENSOR_PZEM_TIMER), TIM_SR_UIF)) { // update event happened
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timer_clear_flag(TIM(SENSOR_PZEM_TIMER), TIM_SR_UIF); // clear flag
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if (tx_i<LENGTH(tx_buffer)) { // bytes are waiting to be sent
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usart_enable_tx_interrupt(USART(SENSOR_PZEM_USART)); // enable interrupt to start sending bytes
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}
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}
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}
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@ -16,7 +16,7 @@
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* @file sensor_pzem.h
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* @author King Kévin <kingkevin@cuvoodoo.info>
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* @date 2016
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* @note peripherals used: USART @ref sensor_pzem_usart
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* @note peripherals used: USART @ref sensor_pzem_usart, timer @ref sensor_pzem_timer
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*/
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#pragma once
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