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Wow, I wasn't even monitoring inputs correctly. Clearly I am rusty in the AVR ways

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XANTRONIX Development 2016-06-03 16:54:39 -05:00
parent 84b5d6a2c9
commit bdf0b3b4e0
1 changed files with 27 additions and 11 deletions
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30
avr/send.c
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@ -35,22 +35,37 @@ static volatile uint8_t device = 0x00,
static volatile uint16_t i = 0,
b = 0;
/*
* So like, we're abusing pins here. So badly, it's beyond. So here's what's
* going down: We want to retain the same physical I/O connections between
* both the sending and receiving flavors of the whole Game Boy Printer
* endeavor, and that means that we must absolutely bit bang MOSI and MISO
* opposite from their ordinary roles. The reason being: There is no notion
* of MISO or MOSI from the Game Boy's (nor its peripherals') point of view.
* The SI and SO pins over a link cable are crossed over, so SI on one end
* always connects to SO on the other, and vice-versa.
*/
static void spi_start() {
/*
* Configure MISO as input
* Configure MISO as output...Oddly
*/
DDRB &= ~(1 << DDB4);
DDRB |= (1 << DDB4);
/*
* Configure MOSI as output
* Configure MOSI as input...Also oddly
*/
DDRB |= (1 << DDB3);
DDRB &= ~(1 << DDB3);
/*
* Configure SCK pin as output
*/
DDRB |= (1 << DDB5);
/*
* Set output pins clear by default
*/
PORTB &= ~((1 << PORTB5) | (1 << PORTB4));
/*
* Set timer clock divider to 1/1
*/
@ -73,6 +88,7 @@ static void spi_start() {
}
static void spi_end() {
PORTB &= ~((1 << PORTB5) | (1 << PORTB4));
DDRB &= ~((1 << DDB5) | (1 << DDB4) | (1 << DDB3));
TIMSK1 &= ~ (1 << OCIE1A);
TCNT1 = 0;
@ -85,14 +101,14 @@ ISR(TIMER1_COMPA_vect) {
PORTB |= (1 << PORTB5);
if (PORTB & (1 << PORTB4)) {
if (PINB & (1 << PINB3)) {
value_in |= 0x80;
}
if (value_out & 0x80) {
PORTB |= (1 << PORTB3);
PORTB |= (1 << PORTB4);
} else {
PORTB &= ~(1 << PORTB3);
PORTB &= ~(1 << PORTB4);
}
value_out <<= 1;