void ow_write_bit(uint8_t bit)
{
bus_low();
if(bit)
{
_delay_us(T/6); // Logic 1
bus_release();
_delay_us(5*T/6); // Finish time slot
}
else
{
_delay_us(T); // Logic 0
bus_release();
}
}
/* One Wire functions */
uint8_t ow_reset(void)
{
// Wait until the bus is high
bus_release();
while( !(OW_BUS_PIN & OW_BUS_PIN_MASK));
uint8_t r = 0;
bus_low();
_delay_us(10*T);
bus_release();
_delay_us(2*T);
r = !bus_read();
_delay_us(6*T);
return r;
}
void tm_fetch_ram ( void ) {
bus_grab_and_wait();
bus_read_block ( ram_textmode, TM_VRAM_FB, TM_PAGE_STRIDE );
bus_read_block ( ram_textattr, TM_VRAM_ATTR, TM_PAGE_STRIDE );
bus_read_block ( &ram_spritecount, TM_SPRITE_ACTIVE, 1 );
bus_read_block ( ram_spritelist, TM_SPRITE_LIST_BASE, ( ram_spritecount * TM_SPRITE_CELL_STRIDE) );
bus_release();
return;
}
uint8_t ow_read_bit(void)
{
int8_t r;
bus_low();
_delay_us(T/6);
bus_release();
_delay_us(T/12);
r = bus_read();
_delay_us(T/12+T/6+T/2);
return r;
}
static uint8_t read_slot()
{
bus_drive0();
_delay_us(MIN_READ_DRIVE_DELAY);
bus_release();
_delay_us(MAX_READ_RESP_DELAY);
const uint8_t value = bus_latch();
// This delay is longer than required, but that's fine
_delay_us(MIN_RWSLOT_MIN_SLOT_LENGTH + MIN_RWSLOT_RECOVERY_DELAY);
return value;
}
uint8_t onewire_reset()
{
// Make the pin an output and drive low for MIN_RESET_PULSE
bus_drive0();
_delay_us(MIN_RESET_PULSE);
bus_release();
// Stop driving the pin and let the DS180B20 do its thing
_delay_us(MIN_PRESENCE_RESP_DELAY + MIN_PRESENCE_PULSE);
const uint8_t presence_value = bus_latch();
// Presence lasts minimum 480us -- this is overkill, that fine.
_delay_us(MIN_RESET_PULSE);
return (presence_value == 0) ? 1 : 0;
}
static void write_slot(const uint8_t value)
{
bus_drive0();
if(value == 0)
{
_delay_us(MIN_RWSLOT_MIN_SLOT_LENGTH);
}
else
{
_delay_us(MIN_WRITE1_DRIVE_DELAY);
}
bus_release();
// Extraneous for write1 case, but harmless
_delay_us(MIN_RWSLOT_MIN_SLOT_LENGTH + MIN_RWSLOT_RECOVERY_DELAY);
}
int main(void) {
system_cm3_setup();
log_setup();
queue_setup();
init_usart1 ( 38400 ); // initialize USART1 @ 9600 baud
init_usart2 ( 38400 );
//USART_puts ( USART1, "Init usart1 complete! Hello World!\r\n" );
USART_puts ( USART2, "Init usart2 complete! Hello World!\r\n" );
fb_setup();
#ifdef VGA_DMA
vga_setup ( VGA_USE_DMA );
#else
vga_setup ( VGA_NO_DMA );
#endif
#ifdef BUS_FRAMEBUFFER
bus_setup();
#endif
//fb_test_pattern ( fb_active, fbt_topbottom );
fb_test_pattern ( fb_active, fbt_offset_squares );
//fb_test_pattern ( fb_active, fbt_vlines );
//fb_test_pattern ( fb_active, fbt_v1lines );
//fb_test_pattern ( fb_active, fbt_onoff1 );
//fb_test_pattern ( fb_active, fbt_spriteram );
while ( 1 ) {
// weeeeee!
// any work for us to do?
#ifdef RUNMODE_COMMAND_SERIAL
if ( vblank ) {
if ( queueready() ) {
command_queue_run();
}
}
#endif
#ifdef RUNMODE_FRAMEBUFFER_FOREVER
if ( vblank ) {
queueit ( "BD" );
command_queue_run();
}
#endif
// update framebuffers
#if 0
if ( vblank ) {
unsigned char i = 0;
fb_clone ( fb_2, fb_active );
while ( vblank ) {
__asm__("nop");
}
fb_test_pattern ( fb_2, i & 0x03 );
i++;
}
#endif
// check for external RAM updates?
#ifdef zzBUS_FRAMEBUFFER
static uint16_t _done = 0;
_done++;
if ( vblank && _done > 30 && _done < 40 ) {
bus_grab_and_wait();
uint32_t addr = 0x1C0000;
uint8_t v;
uint8_t i;
char b [ 2 ];
USART_puts_optional ( USART2, "+REM cart dump: " );
for ( i = 0; i < 20; i++ ) {
v = bus_perform_read ( addr );
b [ 0 ] = v;
b [ 1 ] = '\0';
USART_puts_optional ( USART2, b );
addr++;
}
USART_puts_optional ( USART2, "+++\n" );
bus_release();
}
#endif
// handle queued logs
#if 0
if ( logready() ) {
char *log;
while ( ( log = logpull() ) ) {
USART_puts ( USART2, log );
}
}
#endif
__asm__("nop");
}
} // main
