void loop(){
if(uart_has_data()) {
uart_receive_data();
data++;
uart_send_data();
}
}
/**
* Play one round of the contention game. If neither side received the force_master flag,
* they each wait a random amount of time before sending the ping packet. The first to acknowledge
* the other side's ping is the slave. If the two packets conflict, the came ends in a conflict and
* must be run again.
* If after a timeout passes no token has been received, the device assumes that the pad has
* been snapped and is disconnected from its twin.
* @param usb_present gives the usb-connected side precedence if force_master is not set.
*/
ConnectionState uart_play_round(bool force_master, bool usb_present) {
timer_reset();
uint16_t ms = 0;
while (timer_msec() < 1) {} // let uarts settle
if (!force_master) {
hwrng_start();
timer_reset(); while (timer_msec() < 2) {} // wait 2 ms
while (!hwrng_done()) {} // wait for random data to become available
if (!usb_present) {
ms = 3+(hwrng_bits()[0] & 0x3f); // additional delay of 3-67 ms
} else {
ms = 0; // skip additional delay on usb-connected end
}
}
timer_reset();
while (timer_msec() < ms) {
if (uart_has_data()) {
uint8_t b = uart_consume();
if (b == UTOK_GAME_PING) {
uart_send_byte(UTOK_GAME_ACK);
return CS_TWINNED_SLAVE;
} else if (b == UTOK_GAME_ACK) {
return CS_TWINNED_COLLISION;
}
}
}
uart_send_byte(UTOK_GAME_PING);
timer_reset();
ms = 1000 - ms;
while (timer_msec() < ms) {
if (uart_has_data()) {
uint8_t b = uart_consume();
if (b == UTOK_GAME_ACK) {
return CS_TWINNED_MASTER;
} else if (b == UTOK_GAME_PING) {
return CS_TWINNED_COLLISION;
}
}
}
return CS_SINGLE;
}
void uart_factory_reset_confirm() {
uart_send_byte(UTOK_RST_PROPOSE);
while (1) {
if (uart_has_data() && (uart_consume() == UTOK_RST_CONFIRM)) return;
}
}
void uart_receive_data(){
while(!uart_has_data());
data = UDR0;;
}
