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 volatile uint8_t s88_read_count = 0;
  15 uint8_t s88_read_bit = 0;
  16 volatile uint8_t s88_read_phase = 0;
  17 uint8_t s88_data = 0;
  18 RINGBUFFER(s88_buffer, 8);
  19 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         // Only send one packet per check to avoid blocking
  32         if(ringbuffer_fill(s88_buffer)>0)
  33         {
  34                 uint8_t reply[3];
  35                 reply[0] = S88_DATA;
  36                 reply[1] = s88_out_index++;
  37                 reply[2] = ringbuffer_pop(s88_buffer);
  38                 interface_send(reply, sizeof(reply));
  39         }
  40 }
  41
  42 uint8_t s88_command(const uint8_t *cmd_buf, uint8_t cmd_length)
  43 {
  44         if(cmd_buf[0]==S88_READ)
  45         {
  46                 if(cmd_length!=2)
  47                         return LENGTH_ERROR;
  48
  49                 while(s88_read_count || s88_read_phase) ;
  50
  51                 s88_out_index = 0;
  52                 s88_read_phase = 0xF0;
  53                 s88_read_count = cmd_buf[1];
  54         }
  55         else
  56                 return INVALID_COMMAND;
  57
  58         return COMMAND_OK;
  59 }
  60
  61 static inline void s88_tick(void)
  62 {
  63         if(s88_read_phase==0)
  64         {
  65                 if(!s88_read_count || ringbuffer_space(s88_buffer)==0)
  66                         return;
  67
  68                 PORTD |= BIT(CLOCK);
  69         }
  70         else if(s88_read_phase==1)
  71         {
  72                 uint8_t bit = (PIND>>7)&1;
  73                 s88_data = (s88_data<<1)|bit;
  74                 ++s88_read_bit;
  75                 if(s88_read_bit==8)
  76                 {
  77                         ringbuffer_push(s88_buffer, s88_data);
  78
  79                         --s88_read_count;
  80                         s88_read_bit = 0;
  81                 }
  82         }
  83         else if(s88_read_phase==2)
  84                 PORTD &= ~BIT(CLOCK);
  85         else if(s88_read_phase>3)
  86         {
  87                 if(s88_read_phase==0xF0)
  88                         PORTD |= BIT(LOAD);
  89                 else if(s88_read_phase==0xF4)
  90                         PORTD |= BIT(CLOCK);
  91                 else if(s88_read_phase==0xF6)
  92                         PORTD &= ~BIT(CLOCK);
  93                 else if(s88_read_phase==0xFA)
  94                         PORTD |= BIT(RESET);
  95                 else if(s88_read_phase==0xFC)
  96                         PORTD &= ~BIT(RESET);
  97                 else if(s88_read_phase==0xFF)
  98                 {
  99                         s88_data = (PIND>>7)&1;
 100                         ++s88_read_bit;
 101                         PORTD &= ~BIT(LOAD);
 102                 }
 103                 ++s88_read_phase;
 104                 return;
 105         }
 106
 107         s88_read_phase = (s88_read_phase+1)&3;
 108 }
 109
 110 TIMER_SET_CALLBACK(0, s88_tick)