diff options
Diffstat (limited to 'app/timex.c')
| -rw-r--r-- | app/timex.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/app/timex.c b/app/timex.c new file mode 100644 index 0000000..40f43ad --- /dev/null +++ b/app/timex.c @@ -0,0 +1,248 @@ +#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); +} |