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#include "project.h"
/*
* VGA 640x480 mode timings are
*
* 48 640 16 96
* 10 480 33 2
*
* at 25.175 Hz
*
*/
/*
* Two bytes are shown per video frame one starting at
* scanline 70, the other at 255, and there are 15
* scanlines between bits.
*
*/
#define SL_BYTE_1_START 70
#define SL_BIT 15
#define SL_BYTE_2_START 255
#undef PAD
#undef EX
#define SL_ON(byte,bit) ((SL_BYTE_ ## byte ## _START) + (SL_BIT * (bit)))
#define SL_OFF(byte,bit) (SL_ON(byte,bit) + 1)
#define SEND_BIT(byte,bit,data) \
case SL_ON(byte,bit): \
timex_led((data) & 1); \
break; \
case SL_OFF(byte,bit): \
timex_led(1); \
break
#define SEND_BIT_SHIFT(byte,bit,data) \
case SL_ON(byte,bit): \
timex_led((data) & 1); \
data>>=1; \
break; \
case SL_OFF(byte,bit): \
timex_led(1); \
break
#define SEND_BYTE(byte, start, data) \
SEND_BIT(byte,0,start); \
SEND_BIT_SHIFT(byte,1,data); \
SEND_BIT_SHIFT(byte,2,data); \
SEND_BIT_SHIFT(byte,3,data); \
SEND_BIT_SHIFT(byte,4,data); \
SEND_BIT_SHIFT(byte,5,data); \
SEND_BIT_SHIFT(byte,6,data); \
SEND_BIT_SHIFT(byte,7,data); \
SEND_BIT_SHIFT(byte,8,data)
/*
* We ignore the horizontal front/back/sync and drive the system timer at
* the horizontal sync frequency of 31.46875kHz or as close as we can manage
*/
#define BUFFER_SIZE 512
#define TIMEX_BANK GPIOB
#define TIMEX_GPIO GPIO9
ring_t timex_ring;
static uint8_t timex_ring_buf[BUFFER_SIZE];
static inline void timex_led (int v)
{
if (v)
gpio_set (TIMEX_BANK, TIMEX_GPIO);
else
gpio_clear (TIMEX_BANK, TIMEX_GPIO);
}
#define SYNCS 200
typedef enum {
STATE_MAGIC1,
STATE_MAGIC2,
STATE_MAGIC3,
STATE_MAGIC4,
STATE_IDLE,
STATE_SYNC1,
STATE_SYNC2,
STATE_PACKET_HEADER,
STATE_PACKET_DATA,
STATE_PACKET_PAD,
STATE_PACKET_RECOVERY,
} Timex_state;
static int get_data (uint8_t *start, uint8_t *data)
{
static Timex_state state = STATE_MAGIC1;
static unsigned len;
static unsigned pad;
*start = 0;
switch (state) {
case STATE_MAGIC1:
if (ring_empty (&timex_ring))
return 1;
case STATE_IDLE:
if (ring_empty (&timex_ring))
return 1;
state = STATE_SYNC1;
len = SYNCS;
break;
case STATE_SYNC1:
*data = 0x55;
len--;
if (!len) state = STATE_SYNC2;
break;
case STATE_SYNC2:
*data = 0xaa;
state = STATE_PACKET_HEADER;
break;
case STATE_PACKET_HEADER:
if (ring_read_byte (&timex_ring, data)) {
/*No more data*/
state = STATE_MAGIC1;
return 1;
}
len = *data -1 ;
state = STATE_PACKET_DATA;
#ifdef PAD
pad =(*data &1);
#else
pad=0;
#endif
break;
case STATE_PACKET_DATA:
ring_read_byte (&timex_ring, data);
len--;
if (!len) {
#ifdef PAD
len = 20;
#else
len = 10;
#endif
if (pad)
state = STATE_PACKET_PAD;
else
state = STATE_PACKET_RECOVERY;
}
break;
case STATE_PACKET_PAD:
*data=0x00;
state = STATE_PACKET_RECOVERY;
break;
case STATE_PACKET_RECOVERY:
*start = 1;
*data = 0xff;
len--;
if (!len) state = STATE_PACKET_HEADER;
break;
}
return 0;
}
void timex_tick (void)
{
static unsigned line = 0;
static uint8_t data, start;
switch (line) {
case (SL_BYTE_1_START-2):
if (get_data (&start, &data)) {
line = 0;
return;
}
break;
SEND_BYTE (1, start, data);
#ifdef PAD
case (SL_BYTE_2_START-2):
if (get_data (&start, &data)) {
line = 0;
return;
}
break;
SEND_BYTE (2, start, data);
#endif
}
line++;
if (line == 525)
line = 0;
}
#ifdef EX
uint8_t ex[]={
#include "/root/projects/timex_datalink/datalink-1.0.1/fish.h"
};
#endif
void
timex_init (void)
{
ring_init (&timex_ring, timex_ring_buf, sizeof (timex_ring_buf));
#ifdef EX
ring_write(&timex_ring,ex,sizeof(ex));
#endif
gpio_set_mode (TIMEX_BANK, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, TIMEX_GPIO);
timex_led (1);
}
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