Use TX end IRQ instead of busy wait

[openparking.git] / firmware / modbus.c

diff --git a/firmware/modbus.c b/firmware/modbus.c
old mode 100755 (executable)
new mode 100644 (file)
index 937d9d9..2b2a255
--- a/firmware/modbus.c
+++ b/firmware/modbus.c
@@ -5,11 +5,15 @@
  * All bugs by Jan "Yenya" Kasprzak <kas@fi.muni.cz> :-)
  */
 
+#include <avr/eeprom.h>
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <util/atomic.h>
 #include <util/delay.h>
 
+#include "clock.h"
+#include "modbus.h"
+
 #define BUFSIZE 128    // must be a power of two
 
 // configure the control pin
@@ -33,26 +37,45 @@ typedef uint8_t  bufptr_t;
 static volatile bufptr_t rx_bytes, tx_head, tx_tail;
 static volatile uint8_t rxbuf[BUFSIZE], txbuf[BUFSIZE];
 static volatile uint16_t last_rx;
-static volatile uint8_t unit_id;
+#ifndef mb_unit_id
+static uint8_t mb_unit_id;
+#endif
 
 #define UART_BAUD      9600
 #define UBRR_VAL        ((F_CPU + 8UL * UART_BAUD) / (16UL*UART_BAUD) - 1)
-#define wait_one_byte()        _delay_us(10*1000000/UART_BAUD)
 
-#define get_clock()    (TCNT1)
-#define CLOCK_SPEED    (F_CPU/1024)
 /*
  * According to Wikipedia, it is indeed 28 bits = 3.5 bytes without
  * start- and stopbits.
  */
-#define TIMEOUT                (28*CLOCK_SPEED/UART_BAUD)
+#define REQ_TIMEOUT            (28*CLOCK_HZ/UART_BAUD)
+
+uint16_t hold_regs[MB_N_HOLD_REGS];
+
+#if MB_N_HOLD_REGS_EEPROM > 0
+static uint16_t hold_regs_ee[MB_N_HOLD_REGS_EEPROM] EEMEM = {
+       42, 
+       0, 0, 0, 30, 30, 30, 30, 0, 0, 0, 0, 30,
+       (1 << 4) | (1 << 11), // LED 1
+       0, // LED 2
+};
 
-void modbus_init()
+#endif
+
+void modbus_init(uint8_t unit)
 {
        rx_bytes = 0;
        tx_head = tx_tail = 0;
 
-       unit_id = 42;
+       if (unit)
+               mb_unit_id = unit;
+#if MB_N_HOLD_REGS_EEPROM > 0
+       do {
+               int i;
+               for (i = 0; i < MB_N_HOLD_REGS_EEPROM; i++)
+                       hold_regs[i] = eeprom_read_word(&hold_regs_ee[i]);
+       } while (0);
+#endif
 
        ctl_pin_off();
        ctl_pin_setup();
@@ -103,23 +126,75 @@ static uint16_t compute_crc(volatile uint8_t *buf, bufptr_t len)
        return crc;
 }
 
-static void make_exception(uint8_t func, uint8_t code)
+static void make_exception(mb_exception code)
+{
+       txbuf[1] |= 0x80;
+       txbuf[2] = code;
+       tx_head = 3;
+}
+
+#define get_word(ptr, off) (((uint16_t)ptr[off] << 8) | ptr[off+1])
+void put_byte(uint8_t byte)
+{
+       txbuf[tx_head++] = byte;
+}
+
+void put_word(uint16_t word)
+{
+       txbuf[tx_head++] = word >> 8;
+       txbuf[tx_head++] = word & 0xFF;
+}
+
+static mb_exception read_holding_regs(uint16_t start, uint16_t len)
 {
-       txbuf[tx_head++] = unit_id;
-       txbuf[tx_head++] = func | 0x80;
-       txbuf[tx_head++] = code;
+       if (len > BUFSIZE/2 - 3)
+               return MB_ILLEGAL_ADDR;
+
+       if (start < MB_HOLD_REGS_BASE
+               || start + len > MB_HOLD_REGS_BASE + MB_N_HOLD_REGS)
+               return MB_ILLEGAL_ADDR;
+
+       put_byte(2*len);
+
+       start -= MB_HOLD_REGS_BASE;
+       while(len--)
+               put_word(hold_regs[start++]);
+
+       return MB_OK;
+}
+
+static mb_exception write_single_reg(uint16_t reg, uint16_t val)
+{
+       if (reg < MB_HOLD_REGS_BASE
+               || reg >= MB_HOLD_REGS_BASE + MB_N_HOLD_REGS)
+               return MB_ILLEGAL_ADDR;
+
+       if (!hold_reg_is_valid(reg, val))
+               return MB_ILLEGAL_VAL;
+
+       reg -= MB_HOLD_REGS_BASE;
+       hold_regs[reg] = val;
+#if MB_N_HOLD_REGS_EEPROM > 0
+       if (reg < MB_N_HOLD_REGS_EEPROM)
+               eeprom_write_word(&hold_regs_ee[reg], val);
+#endif
+       put_word(reg + MB_HOLD_REGS_BASE);
+       put_word(val);
+
+       return MB_OK;
 }
 
 void modbus_poll()
 {
        bufptr_t packet_len;
        uint16_t crc;
+       uint8_t rv;
 
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
                if (rx_bytes == 0) // nothing received yet
                        return;
 
-               if (get_clock() - last_rx < TIMEOUT) // still receiving
+               if (get_clock() - last_rx < REQ_TIMEOUT) // still receiving
                        return;
 
                if (rx_bytes < 4) { // too short
@@ -127,7 +202,7 @@ void modbus_poll()
                        return;
                }
 
-               if (rxbuf[0] != unit_id) { // not for myself
+               if (rxbuf[0] != mb_unit_id) { // not for myself
                        rx_bytes = 0;
                        return;
                }
@@ -146,13 +221,24 @@ void modbus_poll()
                || (crc >> 8) != rxbuf[packet_len-1]) // bad crc
                goto out;
 
-       tx_head = 0;
+       txbuf[0] = rxbuf[0]; // not mb_unit_id in case it gets changed
+       txbuf[1] = rxbuf[1];
+       tx_head = 2;
 
+       rv = MB_OK;
        switch (rxbuf[1]) { // function
+       case 3:
+               rv = read_holding_regs(get_word(rxbuf, 2), get_word(rxbuf, 4));
+               break;
+       case 6:
+               rv = write_single_reg(get_word(rxbuf, 2), get_word(rxbuf, 4));
+               break;
        default:
-               make_exception(rxbuf[1], 1); // illegal function
+               make_exception(MB_ILLEGAL_FUNC); // illegal function
        }
-
+       
+       if (rv)
+               make_exception(rv);
 send:
        if (tx_head) {
                crc = compute_crc(txbuf, tx_head);
@@ -180,14 +266,19 @@ ISR(USART_RX_vect)
        }
 }
 
+ISR(USART_TX_vect)
+{
+       UCSR0B &= ~_BV(TXCIE0); // disable further IRQs
+       ctl_pin_off();
+}
+
 ISR(USART_UDRE_vect)
 {
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
                if (tx_head == tx_tail) {
+                       UCSR0B |= _BV(TXCIE0); // enable xmit complete irq
                        UCSR0B &= ~_BV(UDRIE0);
                        tx_tail = tx_head = 0;
-                       wait_one_byte(); // FIXME: too long busy-wait
-                       ctl_pin_off();
                } else {
                        UDR0 = txbuf[tx_tail];
                        tx_tail = bufptr_inc(tx_tail);