arducontrol/s88.c

   1 #include <avr/io.h>
   2 #include "interface.h"
   3 #include "ringbuffer.h"
   4 #include "s88.h"
   5 #include "serial.h"
   6 #include "timer.h"
   7
   8 #define RESET PORTD4
   9 #define LOAD PORTD5
  10 #define CLOCK PORTD6
  11 #define DATA PIN7
  12 #define BIT(x) (1<<(x))
  13
  14 static volatile uint8_t s88_read_count = 0;
  15 static uint8_t s88_read_bit = 0;
  16 static volatile uint8_t s88_read_phase = 0;
  17 static uint8_t s88_data = 0;
  18 static RINGBUFFER(s88_buffer, 8);
  19 static uint8_t s88_out_index = 0;
  20
  21 void s88_init(void)
  22 {
  23         DDRD = (DDRD&0x0F)|0x70;
  24         PORTD &= 0x0F;
  25
  26         timer_start_hz(0, 80000, 1);
  27 }
  28
  29 void s88_check(void)
  30 {
  31         /* Check remaining read count before ringbuffer fill.  If it is zero, no
  32         more bytes are arriving in the buffer and the contents can be sent out. */
  33         uint8_t rc = s88_read_count;
  34         uint8_t count = ringbuffer_fill(s88_buffer);
  35         if(count>=4 || (count>0 && !rc))
  36         {
  37                 uint8_t reply[10];
  38
  39                 reply[0] = S88_DATA;
  40                 reply[1] = s88_out_index;
  41                 for(uint8_t i=0; i<count; ++i)
  42                         reply[2+i] = ringbuffer_pop(s88_buffer);
  43                 interface_send(reply, 2+count);
  44                 s88_out_index += count;
  45         }
  46 }
  47
  48 uint8_t s88_command(const uint8_t *cmd_buf, uint8_t cmd_length)
  49 {
  50         if(cmd_buf[0]==S88_READ)
  51         {
  52                 if(cmd_length!=2)
  53                         return LENGTH_ERROR;
  54
  55                 while(s88_read_count || s88_read_phase) ;
  56
  57                 s88_out_index = 0;
  58                 s88_read_phase = 0xF0;
  59                 s88_read_count = cmd_buf[1];
  60         }
  61         else
  62                 return INVALID_COMMAND;
  63
  64         return COMMAND_OK;
  65 }
  66
  67 static inline void s88_tick(void)
  68 {
  69         if(s88_read_phase==0)
  70         {
  71                 if(!s88_read_count || ringbuffer_space(s88_buffer)==0)
  72                         return;
  73
  74                 PORTD |= BIT(CLOCK);
  75         }
  76         else if(s88_read_phase==1)
  77         {
  78                 uint8_t bit = (PIND>>7)&1;
  79                 s88_data = (s88_data<<1)|bit;
  80                 ++s88_read_bit;
  81                 if(s88_read_bit==8)
  82                 {
  83                         ringbuffer_push(s88_buffer, s88_data);
  84
  85                         --s88_read_count;
  86                         s88_read_bit = 0;
  87                 }
  88         }
  89         else if(s88_read_phase==2)
  90                 PORTD &= ~BIT(CLOCK);
  91         else if(s88_read_phase>3)
  92         {
  93                 if(s88_read_phase==0xF0)
  94                         PORTD |= BIT(LOAD);
  95                 else if(s88_read_phase==0xF4)
  96                         PORTD |= BIT(CLOCK);
  97                 else if(s88_read_phase==0xF6)
  98                         PORTD &= ~BIT(CLOCK);
  99                 else if(s88_read_phase==0xFA)
 100                         PORTD |= BIT(RESET);
 101                 else if(s88_read_phase==0xFC)
 102                         PORTD &= ~BIT(RESET);
 103                 else if(s88_read_phase==0xFF)
 104                 {
 105                         s88_data = (PIND>>7)&1;
 106                         ++s88_read_bit;
 107                         PORTD &= ~BIT(LOAD);
 108                 }
 109                 ++s88_read_phase;
 110                 return;
 111         }
 112
 113         s88_read_phase = (s88_read_phase+1)&3;
 114 }
 115
 116 TIMER_SET_CALLBACK(0, s88_tick)