firmware/s88w-r.c

   1 /* $Id$
   2
   3 This file is part of the MSP Märklin suite
   4 Copyright © 2010  Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6
   7 Firmware for wireless S88 receiver module
   8
   9 S88 pinout:
  10 1 - DATA
  11 2 - GND
  12 3 - CLOCK
  13 4 - LOAD
  14 5 - RESET
  15 6 - POWER
  16
  17 ATMega pinout:
  18 D0 - serial RX
  19 D1 - serial TX
  20 D2 - S88 DATA
  21 D3 - S88 CLOCK
  22 D4 - S88 LOAD
  23 D5 - S88 RESET
  24 */
  25
  26 #include <avr/io.h>
  27 #include <avr/interrupt.h>
  28 #include "lcd.h"
  29 #include "serial.h"
  30
  31 #define DATA_OUT PORTD2
  32 #define CLOCK    PIND3
  33 #define LOAD     PIND4
  34 #define RESET    PIND5
  35
  36 #define BIT(n)   (1<<(n))
  37
  38 void receive(uint8_t);
  39 uint8_t hexdigit(uint8_t);
  40 uint8_t decode_hex(uint8_t);
  41
  42 volatile uint8_t rx_buf[7];
  43 volatile uint8_t rx_fill = 0xFF;
  44 volatile uint8_t input[128] = { 0 };
  45 volatile uint8_t latch[128] = { 0 };
  46 uint8_t log_pos = 0;
  47
  48 int main()
  49 {
  50         uint8_t clock_high = 0;
  51         uint8_t bits = 0;
  52         uint8_t n_bits = 8;
  53         uint8_t offset = 0;
  54
  55         DDRD = 0x06;  // 00000110
  56         PIND = 0xC0;  // 11000000
  57         DDRB = 0x20;  // 00100000
  58         PINB = 0x1F;  // 00011111
  59
  60         serial_init(9600);
  61         serial_set_callback(receive);
  62         lcd_init();
  63         lcd_on();
  64         lcd_clear();
  65
  66         sei();
  67
  68         while(1)
  69         {
  70                 uint8_t d_pins;
  71
  72                 d_pins = PIND;
  73
  74                 if(d_pins&BIT(CLOCK))
  75                 {
  76                         if(!clock_high)
  77                         {
  78                                 if(d_pins&BIT(LOAD))
  79                                 {
  80                                         offset = 0;
  81                                         bits = latch[0];
  82                                         n_bits = 8;
  83                                 }
  84                                 else
  85                                 {
  86                                         bits >>= 1;
  87                                         if(!--n_bits)
  88                                         {
  89                                                 ++offset;
  90                                                 bits = latch[offset];
  91                                                 n_bits = 8;
  92                                         }
  93                                 }
  94
  95                                 if(bits&1)
  96                                         PORTD |= BIT(DATA_OUT);
  97                                 else
  98                                         PORTD &= ~BIT(DATA_OUT);
  99
 100                                 clock_high = 1;
 101                         }
 102                 }
 103                 else if(clock_high)
 104                         clock_high = 0;
 105
 106                 if(d_pins&BIT(RESET))
 107                 {
 108                         uint8_t i;
 109                         for(i=0; i<128; ++i)
 110                                 latch[i] = input[i];
 111                 }
 112         }
 113 }
 114
 115 void receive(uint8_t c)
 116 {
 117         if(rx_fill==0xFF)
 118         {
 119                 if(c==':')
 120                         rx_fill = 0;
 121         }
 122         else if(c=='.')
 123         {
 124                 if(rx_fill>=4)
 125                 {
 126                         uint16_t offset;
 127                         uint8_t nibbles;
 128                         uint8_t i;
 129
 130                         offset = (decode_hex(rx_buf[0])<<8) | (decode_hex(rx_buf[1])<<4) | decode_hex(rx_buf[2]);
 131                         nibbles = (offset&3);
 132                         offset >>= 2;
 133                         if(rx_fill>3+nibbles)
 134                         {
 135                                 for(i=0; i<=nibbles; ++i)
 136                                 {
 137                                         uint16_t j = offset+nibbles-i;
 138                                         uint8_t shift = 4*(j&1);
 139                                         uint8_t bits = decode_hex(rx_buf[3+i]);
 140                                         input[j/2] = (input[j/2]&~(0xF<<shift)) | (bits<<shift);
 141                                         latch[j/2] = input[j/2];
 142                                 }
 143                         }
 144
 145                         lcd_gotoxy(0, 0);
 146                         for(i=10; i--;)
 147                         {
 148                                 lcd_write(hexdigit(input[i]>>4));
 149                                 lcd_write(hexdigit(input[i]));
 150                         }
 151                 }
 152                 rx_fill = 0xFF;
 153         }
 154         else
 155         {
 156                 if(rx_fill<sizeof(rx_buf))
 157                         rx_buf[rx_fill++] = c;
 158                 else
 159                         rx_fill = 0xFF;
 160         }
 161
 162         lcd_gotoxy(log_pos%20, 1+log_pos/20);
 163         lcd_write(c);
 164         ++log_pos;
 165         if(log_pos>=60)
 166                 log_pos = 0;
 167         lcd_gotoxy(log_pos%20, 1+log_pos/20);
 168         lcd_write(255);
 169 }
 170
 171 uint8_t hexdigit(uint8_t n)
 172 {
 173         n &= 0xF;
 174         if(n<10)
 175                 return '0'+n;
 176         else
 177                 return 'A'+(n-0xA);
 178 }
 179
 180 uint8_t decode_hex(uint8_t c)
 181 {
 182         if(c>='0' && c<='9')
 183                 return c-'0';
 184         else if(c>='A' && c<='F')
 185                 return 0xA+(c-'A');
 186         else
 187                 return 0;
 188 }