// TODO: send using interrupt if available
uint8_t ps2_host_send(uint8_t data)
{
uint8_t res = 0;
bool parity = true;
ps2_error = PS2_ERR_NONE;
#ifdef PS2_USE_INT
PS2_INT_OFF();
#endif
/* terminate a transmission if we have */
inhibit();
_delay_us(200); // at least 100us
/* start bit [1] */
data_lo();
clock_hi();
WAIT(clock_lo, 20000, 10); // may take 15ms at most until device starts clocking
/* data [2-9] */
for (uint8_t i = 0; i < 8; i++) {
_delay_us(15);
if (data&(1<<i)) {
parity = !parity;
data_hi();
} else {
data_lo();
}
WAIT(clock_hi, 50, 2);
WAIT(clock_lo, 50, 3);
}
/* parity [10] */
_delay_us(15);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_hi, 50, 4);
WAIT(clock_lo, 50, 5);
/* stop bit [11] */
_delay_us(15);
data_hi();
/* ack [12] */
WAIT(data_lo, 50, 6);
WAIT(clock_lo, 50, 7);
/* wait for idle state */
WAIT(clock_hi, 50, 8);
WAIT(data_hi, 50, 9);
#ifdef PS2_USE_INT
PS2_INT_ON();
#endif
res = ps2_host_recv_response();
ERROR:
#ifdef PS2_USE_INT
PS2_INT_ON();
idle();
#else
inhibit();
#endif
return res;
}
uint8_t ps2_host_send(uint8_t data)
{
bool parity = true;
ps2_error = PS2_ERR_NONE;
PS2_USART_OFF();
/* terminate a transmission if we have */
inhibit();
_delay_us(100); // [4]p.13
/* 'Request to Send' and Start bit */
data_lo();
clock_hi();
WAIT(clock_lo, 10000, 10); // 10ms [5]p.50
/* Data bit[2-9] */
for (uint8_t i = 0; i < 8; i++) {
_delay_us(15);
if (data&(1<<i)) {
parity = !parity;
data_hi();
} else {
data_lo();
}
WAIT(clock_hi, 50, 2);
WAIT(clock_lo, 50, 3);
}
/* Parity bit */
_delay_us(15);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_hi, 50, 4);
WAIT(clock_lo, 50, 5);
/* Stop bit */
_delay_us(15);
data_hi();
/* Ack */
WAIT(data_lo, 50, 6);
WAIT(clock_lo, 50, 7);
/* wait for idle state */
WAIT(clock_hi, 50, 8);
WAIT(data_hi, 50, 9);
idle();
PS2_USART_INIT();
PS2_USART_RX_INT_ON();
return ps2_host_recv_response();
ERROR:
idle();
PS2_USART_INIT();
PS2_USART_RX_INT_ON();
return 0;
}
/*
Host to Keyboard
----------------
Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
____ __ __ __ __ __ __ __ __ __ ________
Clock \______/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
^ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
Data ____|__/ X____X____X____X____X____X____X____X____X____X \___
| Start 0 1 2 3 4 5 6 7 P Stop
Request by host
Start bit: can be long as 300-350us.
Request: Host pulls Clock line down to request to send a command.
Timing: After Request keyboard pull up Data and down Clock line to low for start bit.
After request host release Clock line once Data line becomes hi.
Host writes a bit while Clock is hi and Keyboard reads while low.
Stop bit: Host releases or pulls up Data line to hi after 9th clock and waits for keyboard pull down the line to lo.
*/
uint8_t ibm4704_send(uint8_t data)
{
bool parity = true; // odd parity
ibm4704_error = 0;
IBM4704_INT_OFF();
/* Request to send */
idle();
clock_lo();
/* wait for Start bit(Clock:lo/Data:hi) */
WAIT(data_hi, 300, 0x30);
/* Data bit */
for (uint8_t i = 0; i < 8; i++) {
WAIT(clock_hi, 100, 0x40+i);
if (data&(1<<i)) {
parity = !parity;
data_hi();
} else {
data_lo();
}
WAIT(clock_lo, 100, 0x48+i);
}
/* Parity bit */
WAIT(clock_hi, 100, 0x34);
if (parity) { data_hi(); } else { data_lo(); }
WAIT(clock_lo, 100, 0x35);
/* Stop bit */
WAIT(clock_hi, 100, 0x34);
data_hi();
/* End */
WAIT(data_lo, 100, 0x36);
idle();
IBM4704_INT_ON();
return 0;
ERROR:
idle();
if (ibm4704_error > 0x30) {
xprintf("S:%02X ", ibm4704_error);
}
IBM4704_INT_ON();
return -1;
}
uint8_t m0110_send(uint8_t data)
{
m0110_error = 0;
request();
WAIT_MS(clock_lo, 250, 1); // keyboard may block long time
for (uint8_t bit = 0x80; bit; bit >>= 1) {
WAIT_US(clock_lo, 250, 3);
if (data&bit) {
data_hi();
} else {
data_lo();
}
WAIT_US(clock_hi, 200, 4);
}
_delay_us(100); // hold last bit for 80us
idle();
return 1;
ERROR:
print("m0110_send err: "); phex(m0110_error); print("\n");
_delay_ms(500);
idle();
return 0;
}
static inline void idle(void)
{
clock_hi();
data_hi();
}
/* inhibit device to send */
static inline void inhibit(void)
{
clock_lo();
data_hi();
}