implement timer for reliable message transmission
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@ -16,7 +16,7 @@
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* @file sensor_sdm120.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_sdm120_usart , GPIO @ref sensor_sdm120_gpio
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* @note peripherals used: USART @ref sensor_sdm120_usart , GPIO @ref sensor_sdm120_gpio , timer @ref sensor_sdm120_timer
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*/
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/* standard libraries */
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#include <stdint.h> // standard integer types
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@ -27,6 +27,7 @@
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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/stm32/timer.h> // timer utilities
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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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@ -47,6 +48,13 @@
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#define SENSOR_SDM120_REDE_PIN 12 /**< GPIO pin for RS-485 receiver and driver output enable signal */
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/** @} */
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/** @defgroup sensor_sdm120_timer timer peripheral to enforce waiting time between messages
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* @note 60 ms are recommended between messages in SDM630 ModBus protocol implementation and this seem to also apply to SDM120
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* @{
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*/
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#define SENSOR_SDM120_TIMER 3 /**< timer number to count time */
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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[9] = {0}; /**< buffer for received response (ModBus response messages can be 2+256+2 long but we will only read up to 2 registers) */
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static volatile uint8_t rx_used = 0; /**< number of received data bytes in buffer */
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@ -55,6 +63,16 @@ static volatile uint8_t tx_used = 0; /**< number of byte to transmit */
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volatile bool sensor_sdm120_measurement_received = false;
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/**< the ModBus timeouts to respect for sending messages **/
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static enum timeout_t {
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TIMEOUT_BEGIN = 0, /**< silent time before sending data */
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TIMEOUT_END, /**< silent time after sending data */
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TIMEOUT_BETWEEN, /**< time to wait between messages */
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TIMEOUT_MAX
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} timeout;
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/**< current timeout used */
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static uint16_t timeout_times[TIMEOUT_MAX] = {0};
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/** SDM120 3xxxx input register start addresses for the measurement types */
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static const uint16_t register_input[] = {
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0x0000, // 30001 voltage (in volts)
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@ -106,7 +124,7 @@ static uint16_t crc_modbus(uint8_t* buffer, uint8_t size)
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return crc;
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}
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void sensor_sdm120_setup(void)
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void sensor_sdm120_setup(uint32_t baudrate)
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{
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// enable USART I/O peripheral
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rcc_periph_clock_enable(RCC_AFIO); // enable pin alternate function (USART)
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@ -117,7 +135,7 @@ void sensor_sdm120_setup(void)
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gpio_clear(USART_PORT(SENSOR_SDM120_USART), USART_PIN_RX(SENSOR_SDM120_USART)); // pull down to avoid noise when not connected (it will be set low by RS485 chip when RO is enabled)
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// setup USART parameters for electricity meter
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usart_set_baudrate(USART(SENSOR_SDM120_USART), 9600); // get baud rate by scrolling through the measurements on the electricity meter's screen (default 2400)
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usart_set_baudrate(USART(SENSOR_SDM120_USART), baudrate); // get baud rate by scrolling through the measurements on the electricity meter's screen (default 2400)
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usart_set_databits(USART(SENSOR_SDM120_USART), 8);
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usart_set_stopbits(USART(SENSOR_SDM120_USART), USART_STOPBITS_1);
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usart_set_mode(USART(SENSOR_SDM120_USART), USART_MODE_TX_RX);
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@ -133,6 +151,19 @@ void sensor_sdm120_setup(void)
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gpio_set_mode(GPIO(SENSOR_SDM120_REDE_PORT), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(SENSOR_SDM120_REDE_PIN)); // setup GPIO pin for receiver and driver output enable pin
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gpio_clear(GPIO(SENSOR_SDM120_REDE_PORT),GPIO(SENSOR_SDM120_REDE_PIN)); // disable driver output and enable receive output
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// setup timer to wait for minimal time before sending transmitting
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rcc_periph_clock_enable(RCC_TIM(SENSOR_SDM120_TIMER)); // enable clock for timer block
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timer_reset(TIM(SENSOR_SDM120_TIMER)); // reset timer state
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timer_set_mode(TIM(SENSOR_SDM120_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_SDM120_TIMER)); // stop counter after update event (we only need to count down once)
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timer_set_prescaler(TIM(SENSOR_SDM120_TIMER), 80-1); // set the prescaler so this 16 bits timer allows to wait for 60 ms ( 1/(72E6/66/(2**16))=60.07ms )
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timeout_times[TIMEOUT_BEGIN] = (rcc_ahb_frequency/(TIM_PSC(TIM(SENSOR_SDM120_TIMER))+1))/baudrate/8/2.5; // wait at least 2.5 characters before sending data
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timeout_times[TIMEOUT_END] = (rcc_ahb_frequency/(TIM_PSC(TIM(SENSOR_SDM120_TIMER))+1))/baudrate/8/2.5; // wait at least 2.5 characters after sending data
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timeout_times[TIMEOUT_BETWEEN] = 0.06*(rcc_ahb_frequency/(TIM_PSC(TIM(SENSOR_SDM120_TIMER))+1)); // wait at least 60 ms before sending the next message
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timer_clear_flag(TIM(SENSOR_SDM120_TIMER), TIM_SR_UIF); // clear flag
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timer_enable_irq(TIM(SENSOR_SDM120_TIMER), TIM_DIER_UIE); // enable update interrupt for timer
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nvic_enable_irq(NVIC_TIM_IRQ(SENSOR_SDM120_TIMER)); // allow interrupt for timer just to wake up
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// reset states
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tx_used = 0;
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rx_used = 0;
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@ -148,9 +179,6 @@ void sensor_sdm120_setup(void)
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*/
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static bool sensor_sdm120_transmit_request(uint8_t meter_id, uint8_t function, uint16_t address, float value)
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{
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if (tx_used!=0) { // transmission is ongoing
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return false;
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}
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if (meter_id==0) { // broadcast request are not supported
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return false;
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}
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@ -160,6 +188,10 @@ static bool sensor_sdm120_transmit_request(uint8_t meter_id, uint8_t function, u
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if (address%2) { // even register addresses are not supported by device
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return false;
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}
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while (tx_used) { // transmission is ongoing
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__WFI(); // wait until something happens (transmission ended)
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}
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// build request packet
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uint8_t packet[11]; // buffer to build ModBus message (without error check)
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uint8_t packet_size = 0; // ModBus message size (without error check)
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packet[0] = meter_id; // set slave device address
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@ -189,10 +221,16 @@ static bool sensor_sdm120_transmit_request(uint8_t meter_id, uint8_t function, u
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tx_used = packet_size+2; // set request size
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rx_used = 0; // reset reset buffer
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sensor_sdm120_measurement_received = false; // reset measurement flag
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while (TIM_CR1(TIM(SENSOR_SDM120_TIMER))&TIM_CR1_CEN) { // timer is already used
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__WFI(); // wait until something happens (timer is available again)
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}
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gpio_set(GPIO(SENSOR_SDM120_REDE_PORT),GPIO(SENSOR_SDM120_REDE_PIN)); // enable driver output and disable receive output
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USART_SR(USART(SENSOR_SDM120_USART)) &= USART_SR_TXE; // clear interrupt flag
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usart_enable_tx_interrupt(USART(SENSOR_SDM120_USART)); // enable interrupt to send other bytes
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usart_send(USART(SENSOR_SDM120_USART),tx_buffer[--tx_used]); // start transmission
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// start timeout
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timeout = TIMEOUT_BEGIN; // select time before sending message
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timer_set_period(TIM(SENSOR_SDM120_TIMER), timeout_times[timeout]); // set corresponding timeout
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timer_set_counter(TIM(SENSOR_SDM120_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_SDM120_TIMER)); // wait
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return true;
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}
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@ -276,7 +314,10 @@ void USART_ISR(SENSOR_SDM120_USART)(void)
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if (usart_get_interrupt_source(USART(SENSOR_SDM120_USART), USART_SR_TC)) { // data has been completely transmitted
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USART_CR1(USART(SENSOR_SDM120_USART)) |= USART_CR1_TCIE; // disable transfer complete interrupt
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USART_SR(USART(SENSOR_SDM120_USART)) &= ~USART_SR_TC; // clear flag
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gpio_clear(GPIO(SENSOR_SDM120_REDE_PORT),GPIO(SENSOR_SDM120_REDE_PIN)); // disable driver output and enable receive output
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timeout = TIMEOUT_END; // select wait time after sending data
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timer_set_period(TIM(SENSOR_SDM120_TIMER), timeout_times[timeout]); // set corresponding timeout
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timer_set_counter(TIM(SENSOR_SDM120_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_SDM120_TIMER)); // wait
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}
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if (usart_get_interrupt_source(USART(SENSOR_SDM120_USART), USART_SR_RXNE)) { // data has been received
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if (gpio_get(GPIO(SENSOR_SDM120_REDE_PORT),GPIO(SENSOR_SDM120_REDE_PIN))) { // not in receiver mode
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@ -295,5 +336,35 @@ void USART_ISR(SENSOR_SDM120_USART)(void)
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} else { // buffer full and unknown response received
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USART_SR(USART(SENSOR_SDM120_USART)) &= ~USART_SR_RXNE; // clear flag (wait for user to read measurement, this clears the buffer)
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}
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timeout = TIMEOUT_END; // select time after receiving data
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timer_set_period(TIM(SENSOR_SDM120_TIMER), timeout_times[timeout]); // set corresponding timeout
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timer_set_counter(TIM(SENSOR_SDM120_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_SDM120_TIMER)); // wait
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}
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}
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void TIM_ISR(SENSOR_SDM120_TIMER)(void)
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{
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if (timer_get_flag(TIM(SENSOR_SDM120_TIMER), TIM_SR_UIF)) { // update event happened
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timer_clear_flag(TIM(SENSOR_SDM120_TIMER), TIM_SR_UIF); // clear flag
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// because of the one pulse mode the timer is stopped automatically
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switch (timeout) { // timeout before action passed
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case (TIMEOUT_BEGIN): // we can now send the data
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USART_SR(USART(SENSOR_SDM120_USART)) &= USART_SR_TXE; // clear interrupt flag
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usart_enable_tx_interrupt(USART(SENSOR_SDM120_USART)); // enable interrupt to send other bytes
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usart_send(USART(SENSOR_SDM120_USART),tx_buffer[--tx_used]); // start transmission
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break;
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case (TIMEOUT_END): // we now have to wait before sending the next message
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gpio_clear(GPIO(SENSOR_SDM120_REDE_PORT),GPIO(SENSOR_SDM120_REDE_PIN)); // disable driver output (and enable receive output)
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timeout = TIMEOUT_BETWEEN; // select time between sending message
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timer_set_period(TIM(SENSOR_SDM120_TIMER), timeout_times[timeout]); // set corresponding timeout
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timer_set_counter(TIM(SENSOR_SDM120_TIMER), 0); // reset timer counter to get preset waiting time
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timer_enable_counter(TIM(SENSOR_SDM120_TIMER)); // wait
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case (TIMEOUT_BETWEEN): // nothing to do, we are allowed to send the next message
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break;
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default:
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break;
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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_sdm120.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_sdm120_usart , GPIO @ref sensor_sdm120_gpio
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* @note peripherals used: USART @ref sensor_sdm120_usart , GPIO @ref sensor_sdm120_gpio , timer @ref sensor_sdm120_timer
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*/
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#pragma once
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@ -54,8 +54,10 @@ enum sensor_sdm120_configuration_type_t {
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SENSOR_SDM120_CONFIGURATION_MAX
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};
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/** setup peripherals to communicate with electricity meter */
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void sensor_sdm120_setup(void);
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/** setup peripherals to communicate with electricity meter
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* @param[in] baudrate baud rate of RS485 serial communication
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*/
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void sensor_sdm120_setup(uint32_t baudrate);
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/** request measurement from electricity meter
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* @param[in] meter_id electricity meter device ID
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* @param[in] type measurement type to request
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