215 lines
9.8 KiB
C
215 lines
9.8 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/** library to query measurements from peacefair PZEM-004 and PZEM-004T electricity meter (code)
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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, timer @ref sensor_pzem_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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#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/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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/** @defgroup sensor_pzem_usart USART peripheral used for communication with electricity meter
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* @{
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*/
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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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static uint8_t tx_buffer[7] = {0}; /**< buffer for request to transmit */
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static volatile uint8_t tx_i = 0; /**< current position of transmitted data */
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volatile bool sensor_pzem_measurement_received = false;
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void sensor_pzem_setup(void)
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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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rcc_periph_clock_enable(USART_PORT_RCC(SENSOR_PZEM_USART)); // enable clock for USART port peripheral
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rcc_periph_clock_enable(USART_RCC(SENSOR_PZEM_USART)); // enable clock for USART peripheral
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gpio_set_mode(USART_PORT(SENSOR_PZEM_USART), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_PIN_TX(SENSOR_PZEM_USART)); // setup GPIO pin USART transmit
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gpio_set_mode(USART_PORT(SENSOR_PZEM_USART), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_PIN_RX(SENSOR_PZEM_USART)); // setup GPIO pin USART receive
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gpio_set(USART_PORT(SENSOR_PZEM_USART), USART_PIN_RX(SENSOR_PZEM_USART)); // pull up to avoid noise when not connected
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/* setup USART parameters for electricity meter: 9600 8N1 */
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usart_set_baudrate(USART(SENSOR_PZEM_USART), 9600); // the electricity meter uses a fixed baud rate of 9600 bps
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usart_set_databits(USART(SENSOR_PZEM_USART), 8);
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usart_set_stopbits(USART(SENSOR_PZEM_USART), USART_STOPBITS_1);
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usart_set_mode(USART(SENSOR_PZEM_USART), USART_MODE_TX_RX);
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usart_set_parity(USART(SENSOR_PZEM_USART), USART_PARITY_NONE);
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usart_set_flow_control(USART(SENSOR_PZEM_USART), USART_FLOWCONTROL_NONE);
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nvic_enable_irq(USART_IRQ(SENSOR_PZEM_USART)); // enable the USART interrupt
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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 = 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<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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return;
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}
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tx_buffer[0] = 0xB0+type; // set request nibble and type nibble
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tx_buffer[1] = (address>>24)&0xff; // set address
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tx_buffer[2] = (address>>16)&0xff; // set address
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tx_buffer[3] = (address>>8)&0xff; // set address
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tx_buffer[4] = (address>>0)&0xff; // set address
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tx_buffer[5] = 0; // only used to set alarm
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tx_buffer[6] = 0; // to calculate checksum (sum of all previous bytes)
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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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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 (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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return measurement;
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}
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if ((rx_buffer[0]&0x0f)>=SENSOR_PZEM_MAX) { // not a valid response type received (actually 4 and 5 are valid, but should not happen when using this code
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return measurement;
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}
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uint8_t checksum = 0; // calculate checksum (sum of all other bytes)
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for (uint8_t i=0; i<LENGTH(rx_buffer)-1; i++) {
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checksum += rx_buffer[i]; // calculate buffer
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}
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if (checksum!=rx_buffer[6]) { // checksum does not match
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return measurement;
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}
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measurement.valid = true; // all checks passed
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measurement.type = rx_buffer[0]&0x0f; // save type
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switch (measurement.type) { // decode value depending on type
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case SENSOR_PZEM_VOLTAGE:
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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]*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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break;
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case SENSOR_PZEM_ENERGY:
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measurement.value.energy = ((uint32_t)rx_buffer[1]<<16)+((uint16_t)rx_buffer[2]<<8)+rx_buffer[3];
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break;
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/* not used in this application
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case SENSOR_PZEM_ADDRESS:
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case SENSOR_PZEM_ALARM:
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break; // no value is returned
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*/
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default:
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measurement.valid = false; // unexpected type
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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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return measurement;
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}
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/** USART interrupt service routine called when data has been transmitted or received */
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void USART_ISR(SENSOR_PZEM_USART)(void)
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{
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if (usart_get_interrupt_source(USART(SENSOR_PZEM_USART), USART_SR_TXE)) { // data has been transmitted
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if (tx_i<LENGTH(tx_buffer)) { // not all bytes transmitted
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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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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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if (rx_i<LENGTH(rx_buffer)) { // receiving response
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rx_buffer[rx_i++] = usart_recv(USART(SENSOR_PZEM_USART)); // put received byte in buffer
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if (rx_i>=LENGTH(rx_buffer)) { // buffer full
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sensor_pzem_measurement_received = true; // notify used response has been received
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}
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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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