+/*
+ * Generic MODBUS Library for STM32
+ *
+ * (c) 2019 Martin Mareš <mj@ucw.cz>
+ */
+
#include "util.h"
#include "modbus.h"
+#include <stddef.h>
+#include <string.h>
+
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>
#include <libopencm3/stm32/timer.h>
+/*** Configuration ***/
+
+// You should set the following parameters in config.h
+
+// USART (pins are expected to be configured by the caller)
+// #define MODBUS_USART USART2
+// #define MODBUS_NVIC_USART_IRQ NVIC_USART2_IRQ
+// #define MODBUS_USART_ISR usart2_isr
+
+// GPIO pin for transmitter enable (pins is expected to be configured by the caller)
+// #define MODBUS_TXEN_GPIO_PORT GPIOA
+// #define MODBUS_TXEN_GPIO_PIN GPIO1
+
+// Timer
+// #define MODBUS_TIMER TIM2
+// #define MODBUS_NVIC_TIMER_IRQ NVIC_TIM2_IRQ
+// #define MODBUS_TIMER_ISR tim2_isr
+
+// Slave address we are responding at
+// #define MODBUS_OUR_ADDRESS 42
+
+// Baud rate
+#ifndef MODBUS_BAUD_RATE
+#define MODBUS_BAUD_RATE 19200
+#endif
+
+// CPU clock frequency
+// #define CPU_CLOCK_MHZ 72
+
+// Receive buffer size (standard specifies 256 bytes, you can make it shorter if necessary)
+#ifndef MODBUS_RX_BUFSIZE
+#define MODBUS_RX_BUFSIZE 256
+#endif
+
+// Transmit buffer size (standard specifies 256 bytes, you can make it shorter if necessary)
+#ifndef MODBUS_TX_BUFSIZE
+#define MODBUS_TX_BUFSIZE 256
+#endif
+
+// Receive timeout in microseconds
+#ifndef MODBUS_RX_TIMEOUT
+#if MODBUS_BAUD_RATE <= 19200
+// For low baud rates, the standard specifies timeout of 1.5 character times
+// (1 character = start bit + 8 data bits + parity bit + stop bit = 11 bits)
+#define MODBUS_RX_TIMEOUT (1000000*11*3/2/MODBUS_BAUD_RATE)
+#else
+// For high rates, the timeout is fixed to 750 μs
+#define MODBUS_RX_TIMEOUT 750
+#endif
+#endif
+
+/*** State ***/
+
enum mb_state {
STATE_RX,
STATE_RX_DONE,
STATE_TX_DONE,
};
-#define RX_BUFSIZE 256
-#define TX_BUFSIZE 256
-
-static byte rx_buf[RX_BUFSIZE];
+static byte rx_buf[MODBUS_RX_BUFSIZE];
static u16 rx_size;
static byte rx_bad;
static byte state; // STATE_xxx
-static byte tx_buf[TX_BUFSIZE];
+static byte *rx_frame;
+static byte *rx_frame_end;
+
+static byte tx_buf[MODBUS_TX_BUFSIZE];
static u16 tx_size;
static u16 tx_pos;
-#define MB_OUR_ADDRESS 42
+static bool check_frame(void);
+static void process_frame(void);
-static void UNUSED xx_write_char(uint c) // FIXME
-{
- usart_set_mode(USART2, USART_MODE_TX);
- gpio_set(GPIOA, GPIO1);
- usart_send_blocking(USART2, c);
- while (!usart_get_flag(USART2, USART_SR_TC))
- ;
- gpio_clear(GPIOA, GPIO1);
- usart_set_mode(USART2, USART_MODE_RX);
-}
+/*** Low-level layer ***/
static void rx_init(void)
{
state = STATE_RX;
rx_size = 0;
rx_bad = 0;
- usart_set_mode(USART2, USART_MODE_RX);
- usart_enable_rx_interrupt(USART2);
+ usart_set_mode(MODBUS_USART, USART_MODE_RX);
+ usart_enable_rx_interrupt(MODBUS_USART);
}
static void rx_done(void)
{
state = STATE_RX_DONE;
- usart_disable_rx_interrupt(USART2);
+ usart_disable_rx_interrupt(MODBUS_USART);
}
static void tx_init(void)
{
state = STATE_TX;
tx_pos = 0;
- gpio_set(GPIOA, GPIO1);
- usart_set_mode(USART2, USART_MODE_TX);
- usart_enable_tx_interrupt(USART2);
+ gpio_set(MODBUS_TXEN_GPIO_PORT, MODBUS_TXEN_GPIO_PIN);
+ usart_set_mode(MODBUS_USART, USART_MODE_TX);
+ usart_enable_tx_interrupt(MODBUS_USART);
}
static void tx_done(void)
{
state = STATE_TX_DONE;
- // usart_disable_tx_interrupt(USART2); // Already done by irq handler
- gpio_clear(GPIOA, GPIO1);
+ // usart_disable_tx_interrupt(MODBUS_USART); // Already done by irq handler
+ gpio_clear(MODBUS_TXEN_GPIO_PORT, MODBUS_TXEN_GPIO_PIN);
}
void modbus_init(void)
{
- timer_set_prescaler(TIM2, 71); // 1 tick = 1 μs
- timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_DOWN);
- timer_update_on_overflow(TIM2);
- timer_disable_preload(TIM2);
- timer_one_shot_mode(TIM2);
- timer_enable_irq(TIM2, TIM_DIER_UIE);
- nvic_enable_irq(NVIC_TIM2_IRQ);
-
- gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO_USART2_RX);
- gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART2_TX);
-
- gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO1);
- gpio_clear(GPIOA, GPIO1);
-
- usart_set_baudrate(USART2, 19200);
- usart_set_databits(USART2, 8);
- usart_set_stopbits(USART2, USART_STOPBITS_1);
- usart_set_parity(USART2, USART_PARITY_NONE);
- // usart_set_parity(USART2, USART_PARITY_EVEN); // FIXME
- usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+ timer_set_prescaler(MODBUS_TIMER, CPU_CLOCK_MHZ-1); // 1 tick = 1 μs
+ timer_set_mode(MODBUS_TIMER, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_DOWN);
+ timer_update_on_overflow(MODBUS_TIMER);
+ timer_disable_preload(MODBUS_TIMER);
+ timer_one_shot_mode(MODBUS_TIMER);
+ timer_enable_irq(MODBUS_TIMER, TIM_DIER_UIE);
+ nvic_enable_irq(MODBUS_NVIC_TIMER_IRQ);
+
+ gpio_clear(MODBUS_TXEN_GPIO_PORT, MODBUS_TXEN_GPIO_PIN);
+
+ usart_set_baudrate(MODBUS_USART, MODBUS_BAUD_RATE);
+ usart_set_databits(MODBUS_USART, 9);
+ usart_set_stopbits(MODBUS_USART, USART_STOPBITS_1);
+ usart_set_parity(MODBUS_USART, USART_PARITY_EVEN);
+ usart_set_flow_control(MODBUS_USART, USART_FLOWCONTROL_NONE);
rx_init();
- nvic_enable_irq(NVIC_USART2_IRQ);
- usart_enable(USART2);
-
-#if 0
- u32 xxx = USART_CR1(USART2);
- usart_set_mode(USART2, USART_MODE_TX);
- gpio_set(GPIOA, GPIO1);
- debug_printf("%08x\n", xxx);
- xx_write_char('\n');
-#endif
+ nvic_enable_irq(MODBUS_NVIC_USART_IRQ);
+ usart_enable(MODBUS_USART);
}
-void usart2_isr(void)
+void MODBUS_USART_ISR(void)
{
- u32 status = USART_SR(USART2);
-
- // FIXME: Optimize
+ u32 status = USART_SR(MODBUS_USART);
if (status & USART_SR_RXNE) {
- uint ch = usart_recv(USART2);
+ uint ch = usart_recv(MODBUS_USART);
if (state == STATE_RX) {
-#if 0
if (status & (USART_SR_FE | USART_SR_ORE | USART_SR_NE)) {
rx_bad = 1;
- } else
-#endif
- if (rx_size < RX_BUFSIZE) {
+ } else if (rx_size < MODBUS_RX_BUFSIZE) {
rx_buf[rx_size++] = ch;
} else {
// Frame too long
rx_bad = 2;
}
- timer_set_period(TIM2, 7500); // 0.75 ms timeout for end of frame (FIXME: right value?)
- timer_generate_event(TIM2, TIM_EGR_UG);
- timer_enable_counter(TIM2);
+ timer_set_period(MODBUS_TIMER, MODBUS_RX_TIMEOUT);
+ timer_generate_event(MODBUS_TIMER, TIM_EGR_UG);
+ timer_enable_counter(MODBUS_TIMER);
}
}
if (state == STATE_TX) {
if (status & USART_SR_TXE) {
if (tx_pos < tx_size) {
- usart_send(USART2, tx_buf[tx_pos++]);
+ usart_send(MODBUS_USART, tx_buf[tx_pos++]);
} else {
// The transmitter is double-buffered, so at this moment, it is transmitting
// the last byte of the frame. Wait until transfer is completed.
- usart_disable_tx_interrupt(USART2);
- USART_CR1(USART2) |= USART_CR1_TCIE;
+ usart_disable_tx_interrupt(MODBUS_USART);
+ USART_CR1(MODBUS_USART) |= USART_CR1_TCIE;
state = STATE_TX_LAST;
}
}
- }
-
- if (state == STATE_TX_LAST) {
+ } else if (state == STATE_TX_LAST) {
if (status & USART_SR_TC) {
// Transfer of the last byte is complete. Release the bus.
- USART_CR1(USART2) &= ~USART_CR1_TCIE;
+ USART_CR1(MODBUS_USART) &= ~USART_CR1_TCIE;
tx_done();
rx_init();
}
}
}
-void tim2_isr(void)
+void MODBUS_TIMER_ISR(void)
{
- if (TIM_SR(TIM2) & TIM_SR_UIF) {
- TIM_SR(TIM2) &= ~TIM_SR_UIF;
+ if (TIM_SR(MODBUS_TIMER) & TIM_SR_UIF) {
+ TIM_SR(MODBUS_TIMER) &= ~TIM_SR_UIF;
if (state == STATE_RX)
rx_done();
}
}
-// CRC tables
+void modbus_loop(void)
+{
+ if (state != STATE_RX_DONE)
+ return;
+ state = STATE_PROCESSING;
+
+ if (!check_frame()) {
+ rx_init();
+ return;
+ }
+
+ if (rx_buf[0] == MODBUS_OUR_ADDRESS) {
+ // Frame addressed to us: process and reply
+ process_frame();
+ tx_init();
+ } else if (rx_buf[0] == 0x00) {
+ // Broadcast frame: process, but do not reply
+ process_frame();
+ rx_init();
+ } else {
+ // Somebody else's frame: discard
+ rx_init();
+ }
+}
+
+/** CRC ***/
static const byte crc_hi[] = {
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
- 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
- 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
- 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
- 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
- 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
- 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
- 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
- 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
- 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
- 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
- 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
- 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
- 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
- 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
+ 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
+ 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
+ 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
+ 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
+ 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
+ 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
+ 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
+ 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
+ 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
+ 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40,
+ 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0, 0x80, 0x41, 0x00, 0xc1,
+ 0x81, 0x40, 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41,
+ 0x00, 0xc1, 0x81, 0x40, 0x01, 0xc0, 0x80, 0x41, 0x01, 0xc0,
+ 0x80, 0x41, 0x00, 0xc1, 0x81, 0x40
};
static const byte crc_lo[] = {
- 0x00, 0xc0, 0xc1, 0x01, 0xc3, 0x03, 0x02, 0xc2, 0xc6, 0x06,
- 0x07, 0xc7, 0x05, 0xc5, 0xc4, 0x04, 0xcc, 0x0c, 0x0d, 0xcd,
- 0x0f, 0xcf, 0xce, 0x0e, 0x0a, 0xca, 0xcb, 0x0b, 0xc9, 0x09,
- 0x08, 0xc8, 0xd8, 0x18, 0x19, 0xd9, 0x1b, 0xdb, 0xda, 0x1a,
- 0x1e, 0xde, 0xdf, 0x1f, 0xdd, 0x1d, 0x1c, 0xdc, 0x14, 0xd4,
- 0xd5, 0x15, 0xd7, 0x17, 0x16, 0xd6, 0xd2, 0x12, 0x13, 0xd3,
- 0x11, 0xd1, 0xd0, 0x10, 0xf0, 0x30, 0x31, 0xf1, 0x33, 0xf3,
- 0xf2, 0x32, 0x36, 0xf6, 0xf7, 0x37, 0xf5, 0x35, 0x34, 0xf4,
- 0x3c, 0xfc, 0xfd, 0x3d, 0xff, 0x3f, 0x3e, 0xfe, 0xfa, 0x3a,
- 0x3b, 0xfb, 0x39, 0xf9, 0xf8, 0x38, 0x28, 0xe8, 0xe9, 0x29,
- 0xeb, 0x2b, 0x2a, 0xea, 0xee, 0x2e, 0x2f, 0xef, 0x2d, 0xed,
- 0xec, 0x2c, 0xe4, 0x24, 0x25, 0xe5, 0x27, 0xe7, 0xe6, 0x26,
- 0x22, 0xe2, 0xe3, 0x23, 0xe1, 0x21, 0x20, 0xe0, 0xa0, 0x60,
- 0x61, 0xa1, 0x63, 0xa3, 0xa2, 0x62, 0x66, 0xa6, 0xa7, 0x67,
- 0xa5, 0x65, 0x64, 0xa4, 0x6c, 0xac, 0xad, 0x6d, 0xaf, 0x6f,
- 0x6e, 0xae, 0xaa, 0x6a, 0x6b, 0xab, 0x69, 0xa9, 0xa8, 0x68,
- 0x78, 0xb8, 0xb9, 0x79, 0xbb, 0x7b, 0x7a, 0xba, 0xbe, 0x7e,
- 0x7f, 0xbf, 0x7d, 0xbd, 0xbc, 0x7c, 0xb4, 0x74, 0x75, 0xb5,
- 0x77, 0xb7, 0xb6, 0x76, 0x72, 0xb2, 0xb3, 0x73, 0xb1, 0x71,
- 0x70, 0xb0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
- 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9c, 0x5c,
- 0x5d, 0x9d, 0x5f, 0x9f, 0x9e, 0x5e, 0x5a, 0x9a, 0x9b, 0x5b,
- 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4b, 0x8b,
- 0x8a, 0x4a, 0x4e, 0x8e, 0x8f, 0x4f, 0x8d, 0x4d, 0x4c, 0x8c,
- 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
- 0x43, 0x83, 0x41, 0x81, 0x80, 0x40
+ 0x00, 0xc0, 0xc1, 0x01, 0xc3, 0x03, 0x02, 0xc2, 0xc6, 0x06,
+ 0x07, 0xc7, 0x05, 0xc5, 0xc4, 0x04, 0xcc, 0x0c, 0x0d, 0xcd,
+ 0x0f, 0xcf, 0xce, 0x0e, 0x0a, 0xca, 0xcb, 0x0b, 0xc9, 0x09,
+ 0x08, 0xc8, 0xd8, 0x18, 0x19, 0xd9, 0x1b, 0xdb, 0xda, 0x1a,
+ 0x1e, 0xde, 0xdf, 0x1f, 0xdd, 0x1d, 0x1c, 0xdc, 0x14, 0xd4,
+ 0xd5, 0x15, 0xd7, 0x17, 0x16, 0xd6, 0xd2, 0x12, 0x13, 0xd3,
+ 0x11, 0xd1, 0xd0, 0x10, 0xf0, 0x30, 0x31, 0xf1, 0x33, 0xf3,
+ 0xf2, 0x32, 0x36, 0xf6, 0xf7, 0x37, 0xf5, 0x35, 0x34, 0xf4,
+ 0x3c, 0xfc, 0xfd, 0x3d, 0xff, 0x3f, 0x3e, 0xfe, 0xfa, 0x3a,
+ 0x3b, 0xfb, 0x39, 0xf9, 0xf8, 0x38, 0x28, 0xe8, 0xe9, 0x29,
+ 0xeb, 0x2b, 0x2a, 0xea, 0xee, 0x2e, 0x2f, 0xef, 0x2d, 0xed,
+ 0xec, 0x2c, 0xe4, 0x24, 0x25, 0xe5, 0x27, 0xe7, 0xe6, 0x26,
+ 0x22, 0xe2, 0xe3, 0x23, 0xe1, 0x21, 0x20, 0xe0, 0xa0, 0x60,
+ 0x61, 0xa1, 0x63, 0xa3, 0xa2, 0x62, 0x66, 0xa6, 0xa7, 0x67,
+ 0xa5, 0x65, 0x64, 0xa4, 0x6c, 0xac, 0xad, 0x6d, 0xaf, 0x6f,
+ 0x6e, 0xae, 0xaa, 0x6a, 0x6b, 0xab, 0x69, 0xa9, 0xa8, 0x68,
+ 0x78, 0xb8, 0xb9, 0x79, 0xbb, 0x7b, 0x7a, 0xba, 0xbe, 0x7e,
+ 0x7f, 0xbf, 0x7d, 0xbd, 0xbc, 0x7c, 0xb4, 0x74, 0x75, 0xb5,
+ 0x77, 0xb7, 0xb6, 0x76, 0x72, 0xb2, 0xb3, 0x73, 0xb1, 0x71,
+ 0x70, 0xb0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
+ 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9c, 0x5c,
+ 0x5d, 0x9d, 0x5f, 0x9f, 0x9e, 0x5e, 0x5a, 0x9a, 0x9b, 0x5b,
+ 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4b, 0x8b,
+ 0x8a, 0x4a, 0x4e, 0x8e, 0x8f, 0x4f, 0x8d, 0x4d, 0x4c, 0x8c,
+ 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
+ 0x43, 0x83, 0x41, 0x81, 0x80, 0x40
};
static u16 crc16(byte *buf, u16 len)
return (hi << 8 | lo);
}
+/*** High-level layer ***/
+
static bool check_frame(void)
{
if (rx_bad) {
return false;
}
+ rx_frame = rx_buf + 1;
+ rx_frame_end = rx_frame + rx_size - 2;
return true;
}
enum mb_function {
+ FUNC_READ_COILS = 0x01,
+ FUNC_READ_DISCRETE_INPUTS = 0x02,
FUNC_READ_HOLDING_REGISTERS = 0x03,
+ FUNC_READ_INPUT_REGISTERS = 0x04,
+ FUNC_WRITE_SINGLE_COIL = 0x05,
+ FUNC_WRITE_SINGLE_REGISTER = 0x06,
+ FUNC_READ_EXCEPTION_STATUS = 0x07,
+ FUNC_DIAGNOSTICS = 0x08,
+ FUNC_GET_COMM_EVENT_COUNTER = 0x0b,
+ FUNC_GET_COMM_EVENT_LOG = 0x0c,
+ FUNC_WRITE_MULTIPLE_COILS = 0x0f,
+ FUNC_WRITE_MULTIPLE_REGISTERS = 0x10,
+ FUNC_REPORT_SLAVE_ID = 0x11,
+ FUNC_READ_FILE_RECORD = 0x14,
+ FUNC_WRITE_FILE_RECORD = 0x15,
+ FUNC_MASK_WRITE_REGISTER = 0x16,
+ FUNC_READ_WRITE_MULTIPLE_REGISTERS = 0x17,
+ FUNC_READ_FIFO_QUEUE = 0x18,
+ FUNC_ENCAPSULATED_INTERFACE_TRANSPORT = 0x2b,
};
enum mb_error {
ERR_ILLEGAL_DATA_VALUE = 0x03,
};
+static uint read_remains(void)
+{
+ return rx_frame_end - rx_frame;
+}
+
+static byte read_byte(void)
+{
+ return *rx_frame++;
+}
+
+static u16 read_u16(void)
+{
+ byte hi = *rx_frame++;
+ byte lo = *rx_frame++;
+ return (hi << 8) | lo;
+}
+
+static void write_byte(byte v)
+{
+ tx_buf[tx_size++] = v;
+}
+
+static void write_u16(u16 v)
+{
+ write_byte(v >> 8);
+ write_byte(v);
+}
+
+static bool body_fits(uint body_len)
+{
+ // body_len excludes slave address, function code, and CRC
+ return (2 + body_len + 2 <= MODBUS_TX_BUFSIZE);
+}
+
static void report_error(byte code)
{
// Discard the partially constructed body of the reply and rewrite the header
tx_size = 3;
}
+static void func_read_bits(bool coils)
+{
+ if (read_remains() < 4)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 start = read_u16();
+ u16 count = read_u16();
+
+ uint bytes = (count+7) / 8;
+ if (!body_fits(1 + bytes))
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < count; i++)
+ if (!(coils ? modbus_check_coil : modbus_check_discrete_input)(start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ write_byte(bytes);
+ for (u16 i = 0; i < bytes; i++) {
+ byte b = 0;
+ for (byte j = 0; j < 8 && 8*i + j < count; j++) {
+ uint addr = start + 8*i + j;
+ if ((coils ? modbus_get_coil : modbus_get_discrete_input)(addr))
+ b |= 1 << j;
+ }
+ write_byte(b);
+ }
+}
+
+static void func_read_registers(byte holding)
+{
+ if (read_remains() < 4)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 start = read_u16();
+ u16 count = read_u16();
+
+ uint bytes = 2*count;
+ if (!body_fits(1 + bytes))
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < count; i++)
+ if (!(holding ? modbus_check_holding_register : modbus_check_input_register)(start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ // FIXME: Reporting of slave failures?
+ write_byte(bytes);
+ for (u16 i = 0; i < count; i++)
+ write_u16((holding ? modbus_get_holding_register : modbus_get_input_register)(start + i));
+}
+
+static void func_write_single_coil(void)
+{
+ if (read_remains() < 4)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 addr = read_u16();
+ u16 value = read_u16();
+
+ if (!modbus_check_coil(addr))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+ if (value != 0x0000 && value != 0xff00)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ modbus_set_coil(addr, value);
+}
+
+static void func_write_single_register(void)
+{
+ if (read_remains() < 4)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 addr = read_u16();
+ u16 value = read_u16();
+
+ if (!modbus_check_holding_register(addr))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ modbus_set_holding_register(addr, value);
+}
+
+static void func_write_multiple_coils(void)
+{
+ if (read_remains() < 5)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 start = read_u16();
+ u16 count = read_u16();
+ byte bytes = read_byte();
+
+ if (read_remains() < bytes || bytes != (count+7) / 8)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < count; i++)
+ if (!modbus_check_coil(start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ for (u16 i = 0; i < count; i++)
+ modbus_set_coil(start + i, rx_frame[i/8] & (1U << (i%8)));
+}
+
+static void func_write_multiple_registers(void)
+{
+ if (read_remains() < 5)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 start = read_u16();
+ u16 count = read_u16();
+ byte bytes = read_byte();
+
+ if (read_remains() < bytes || bytes != 2*count)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < count; i++)
+ if (!modbus_check_holding_register(start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ for (u16 i = 0; i < count; i++)
+ modbus_set_holding_register(start + i, read_u16());
+}
+
+static void func_mask_write_register(void)
+{
+ if (read_remains() < 6)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 addr = read_u16();
+ u16 and_mask = read_u16();
+ u16 or_mask = read_u16();
+
+ if (!modbus_check_holding_register(addr))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ u16 reg = modbus_get_holding_register(addr);
+ reg = (reg & and_mask) | (or_mask & ~and_mask);
+ modbus_set_holding_register(addr, reg);
+}
+
+static void func_read_write_multiple_registers(void)
+{
+ if (read_remains() < 9)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ u16 read_start = read_u16();
+ u16 read_count = read_u16();
+ u16 write_start = read_u16();
+ u16 write_count = read_u16();
+ byte write_bytes = read_byte();
+
+ if (read_remains() < write_bytes || write_bytes != 2*write_count)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < read_count; i++)
+ if (!modbus_check_holding_register(read_start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ for (u16 i = 0; i < write_count; i++)
+ if (!modbus_check_holding_register(write_start + i))
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+
+ byte read_bytes = 2*write_count;
+ if (!body_fits(1 + read_bytes))
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ for (u16 i = 0; i < write_count; i++)
+ modbus_set_holding_register(write_start + i, read_u16());
+
+ write_byte(read_bytes);
+ for (u16 i = 0; i < read_count; i++)
+ modbus_get_holding_register(read_start + i);
+}
+
+static void func_encapsulated_interface_transport(void)
+{
+ if (read_remains() < 3 ||
+ read_byte() != 0x0e)
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+
+ byte action = read_byte();
+ byte id = read_byte();
+
+ byte range_min, range_max;
+ switch (action) {
+ case 1:
+ // Streaming access to basic identification
+ range_min = MODBUS_ID_VENDOR_NAME;
+ range_max = MODBUS_ID_MAJOR_MINOR_REVISION;
+ break;
+ case 2:
+ // Streaming access to regular identification
+ range_min = MODBUS_ID_VENDOR_URL;
+ range_max = MODBUS_ID_USER_APP_NAME;
+ break;
+ case 4:
+ // Individual access
+ if (id >= MODBUS_ID_MAX || !modbus_id_strings[id])
+ return report_error(ERR_ILLEGAL_DATA_ADDRESS);
+ range_min = range_max = id;
+ break;
+ default:
+ return report_error(ERR_ILLEGAL_DATA_VALUE);
+ }
+
+ if (action != 4) {
+ if (id < range_min || id > range_max)
+ id = range_min;
+ }
+
+ write_byte(0x0e); // Repeat a part of the request
+ write_byte(action);
+
+ // Conformity level
+ if (modbus_id_strings[MODBUS_ID_VENDOR_URL] ||
+ modbus_id_strings[MODBUS_ID_PRODUCT_NAME] ||
+ modbus_id_strings[MODBUS_ID_USER_APP_NAME])
+ write_byte(0x82); // Regular identification, both stream and individual access supported
+ else
+ write_byte(0x81); // Basic identification only
+
+ u16 more_follows_at = tx_size;
+ write_byte(0); // More follows: so far not
+ write_byte(0); // Next object ID: so far none
+ write_byte(0); // Number of objects
+
+ for (id = range_min; id <= range_max; id++) {
+ if (modbus_id_strings[id]) {
+ byte len = strlen(modbus_id_strings[id]);
+ byte remains = MODBUS_TX_BUFSIZE - 4 - tx_size; // 2 for CRC, 2 for object header
+ if (len > remains) {
+ // If it is the only object, cut it
+ if (!tx_buf[more_follows_at + 2])
+ len = remains;
+ else {
+ // More follows, report the next ID
+ tx_buf[more_follows_at] = 0xff;
+ tx_buf[more_follows_at + 1] = id;
+ break;
+ }
+ }
+ tx_buf[more_follows_at + 2] ++;
+ write_byte(id);
+ write_byte(len);
+ memcpy(tx_buf + tx_size, modbus_id_strings[id], len);
+ tx_size += len;
+ }
+ }
+}
+
static void process_frame(void)
{
- byte func = rx_buf[1];
+ byte func = read_byte();
// Prepare reply frame
- tx_buf[0] = MB_OUR_ADDRESS;
+ tx_buf[0] = MODBUS_OUR_ADDRESS;
tx_buf[1] = rx_buf[1];
tx_size = 2;
switch (func) {
+ case FUNC_READ_COILS:
+ func_read_bits(true);
+ break;
+ case FUNC_READ_DISCRETE_INPUTS:
+ func_read_bits(false);
+ break;
case FUNC_READ_HOLDING_REGISTERS:
- tx_buf[tx_size++] = 2;
- tx_buf[tx_size++] = 0x12;
- tx_buf[tx_size++] = 0x34;
+ func_read_registers(true);
+ break;
+ case FUNC_READ_INPUT_REGISTERS:
+ func_read_registers(false);
+ break;
+ case FUNC_WRITE_SINGLE_COIL:
+ func_write_single_coil();
+ break;
+ case FUNC_WRITE_SINGLE_REGISTER:
+ func_write_single_register();
+ break;
+ case FUNC_WRITE_MULTIPLE_COILS:
+ func_write_multiple_coils();
+ break;
+ case FUNC_WRITE_MULTIPLE_REGISTERS:
+ func_write_multiple_registers();
+ break;
+ case FUNC_MASK_WRITE_REGISTER:
+ func_mask_write_register();
+ break;
+ case FUNC_READ_WRITE_MULTIPLE_REGISTERS:
+ func_read_write_multiple_registers();
+ break;
+ case FUNC_ENCAPSULATED_INTERFACE_TRANSPORT:
+ func_encapsulated_interface_transport();
break;
default:
report_error(ERR_ILLEGAL_FUNCTION);
}
// Finish reply frame
- u16 crc = crc16(tx_buf, tx_size);
- tx_buf[tx_size++] = crc >> 8;
- tx_buf[tx_size++] = crc;
-}
-
-void modbus_loop(void)
-{
- if (state != STATE_RX_DONE) {
- // gpio_toggle(GPIOC, GPIO13);
- return;
- }
- state = STATE_PROCESSING;
- gpio_toggle(GPIOC, GPIO13);
-
- if (!check_frame()) {
- rx_init();
- return;
- }
-
- if (rx_buf[0] == MB_OUR_ADDRESS) {
- // Frame addressed to us: process and reply
- process_frame();
- tx_init();
- } else if (rx_buf[0] == 0x00) {
- // Broadcast frame: process, but do not reply
- process_frame();
- rx_init();
- } else {
- // Somebody else's frame: discard
- rx_init();
- }
+ write_u16(crc16(tx_buf, tx_size));
}
projects / home-hw.git / blobdiff