#include <stdbool.h>
#include <avr/interrupt.h>
-#include "ringbuf.h"
+#include <util/atomic.h>
#include "ibmpc.h"
#include "debug.h"
#include "timer.h"
} while (0)
-#define BUF_SIZE 16
-static uint8_t buf[BUF_SIZE];
-static ringbuf_t rb = {
- .buffer = buf,
- .head = 0,
- .tail = 0,
- .size_mask = BUF_SIZE - 1
-};
-
-volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_AT;
+volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_NO;
volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
+/* 2-byte buffer for data received from keyhboard
+ * buffer states:
+ * FFFF: empty
+ * FFss: one data
+ * sstt: two data(full)
+ * 0xFF can not be stored as data in buffer because it means empty or no data.
+ */
+static volatile uint16_t recv_data = 0xFFFF;
+/* internal state of receiving data */
+static volatile uint16_t isr_state = 0x8000;
+static uint8_t timer_start = 0;
+
void ibmpc_host_init(void)
{
- clock_init();
- data_init();
- idle();
+ // initialize reset pin to HiZ
+ IBMPC_RST_HIZ();
+ inhibit();
IBMPC_INT_INIT();
+ IBMPC_INT_OFF();
+}
+
+void ibmpc_host_enable(void)
+{
IBMPC_INT_ON();
- // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
- //wait_ms(2500);
+ idle();
+}
+
+void ibmpc_host_disable(void)
+{
+ IBMPC_INT_OFF();
+ inhibit();
}
int16_t ibmpc_host_send(uint8_t data)
bool parity = true;
ibmpc_error = IBMPC_ERR_NONE;
- if (ibmpc_protocol == IBMPC_PROTOCOL_XT) return -1;
-
dprintf("w%02X ", data);
IBMPC_INT_OFF();
WAIT(clock_hi, 50, 8);
WAIT(data_hi, 50, 9);
+ // clear buffer to get response correctly
+ recv_data = 0xFFFF;
+ ibmpc_host_isr_clear();
+
idle();
IBMPC_INT_ON();
return ibmpc_host_recv_response();
return -1;
}
+/*
+ * Receive data from keyboard
+ */
+int16_t ibmpc_host_recv(void)
+{
+ uint16_t data = 0;
+ uint8_t ret = 0xFF;
+
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+ data = recv_data;
+ if ((data&0xFF00) != 0xFF00) { // recv_data:sstt -> recv_data:FFtt, ret:ss
+ ret = (data>>8)&0x00FF;
+ recv_data = data | 0xFF00;
+ } else if (data != 0xFFFF) { // recv_data:FFss -> recv_data:FFFF, ret:ss
+ ret = data&0x00FF;
+ recv_data = data | 0x00FF;
+ }
+ }
+
+ if (ret != 0xFF) dprintf("r%02X ", ret);
+ if (recv_data != 0xFFFF) dprintf("b%04X ", recv_data);
+ return ((ret != 0xFF) ? ret : -1);
+
+}
+
int16_t ibmpc_host_recv_response(void)
{
// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
uint8_t retry = 25;
- while (retry-- && ringbuf_is_empty(&rb)) {
+ int16_t data = -1;
+ while (retry-- && (data = ibmpc_host_recv()) == -1) {
wait_ms(1);
}
- int16_t data = ringbuf_get(&rb);
- if (data != -1) dprintf("r%02X ", data);
return data;
}
-/* get data received by interrupt */
-int16_t ibmpc_host_recv(void)
+void ibmpc_host_isr_clear(void)
{
- int16_t data = ringbuf_get(&rb);
- if (data != -1) dprintf("r%02X ", data);
- return data;
+ isr_state = 0x8000;
+ recv_data = 0xFFFF;
}
+// NOTE: With this ISR data line can be read within 2us after clock falling edge.
+// To read data line early as possible:
+// write naked ISR with asembly code to read the line and call C func to do other job?
ISR(IBMPC_INT_VECT)
{
- static uint16_t last_time = 0;
- static enum {
- START,
- BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
- PARITY,
- STOP,
- } state = START;
- static uint8_t data = 0;
- static uint8_t parity = 1;
-
- uint8_t dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
-
- // Reset state when taking more than 1ms
- if (last_time && timer_elapsed(last_time) > 10) {
- ibmpc_error = IBMPC_ERR_TIMEOUT | IBMPC_ERR_RECV | state;
- state = START;
- data = 0;
- parity = 1;
+ uint8_t dbit;
+ dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
+
+ // Timeout check
+ uint8_t t;
+ // use only the least byte of millisecond timer
+ asm("lds %0, %1" : "=r" (t) : "p" (&timer_count));
+ //t = (uint8_t)timer_count; // compiler uses four registers instead of one
+ if (isr_state == 0x8000) {
+ timer_start = t;
+ } else {
+ // should not take more than 1ms
+ if (timer_start != t && (uint8_t)(timer_start + 1) != t) {
+ ibmpc_error = IBMPC_ERR_TIMEOUT;
+ //goto ERROR;
+ // timeout error recovery by clearing isr_state?
+ timer_start = t;
+ isr_state = 0x8000;
+ }
}
- last_time = timer_read();
-
- switch (state) {
- case START:
- if (ibmpc_protocol == IBMPC_PROTOCOL_XT) {
- // ignore start(0) bit
- if (!dbit) return;
- } else {
- if (dbit)
- goto ERROR;
- }
- case BIT0:
- case BIT1:
- case BIT2:
- case BIT3:
- case BIT4:
- case BIT5:
- case BIT6:
- case BIT7:
- data >>= 1;
- if (dbit) {
- data |= 0x80;
- parity++;
- }
- if (state == BIT7 && ibmpc_protocol == IBMPC_PROTOCOL_XT) {
- if (!ringbuf_put(&rb, data)) {
- ibmpc_error = IBMPC_ERR_FULL;
- goto ERROR;
- }
- ibmpc_error = IBMPC_ERR_NONE;
- goto DONE;
- }
+
+ isr_state = isr_state>>1;
+ if (dbit) isr_state |= 0x8000;
+
+ // isr_state: state of receiving data from keyboard
+ //
+ // This should be initialized with 0x8000 before receiving data and
+ // the MSB '*1' works as marker to discrimitate between protocols.
+ // It stores sampled bit at MSB after right shift on each clock falling edge.
+ //
+ // XT protocol has two variants of signaling; XT_IBM and XT_Clone.
+ // XT_IBM uses two start bits 0 and 1 while XT_Clone uses just start bit 1.
+ // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
+ //
+ // 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+ // -----------------------------------------------------
+ // *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 Initial state(0x8000)
+ //
+ // x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
+ // x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
+ // b6 b5 b4 b3 b2 b1 b0 1 | 0 *1 0 0 0 0 0 0 XT_IBM-midway ^1
+ // b7 b6 b5 b4 b3 b2 b1 b0 | 0 *1 0 0 0 0 0 0 AT-midway ^1
+ // b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 XT_Clone-done
+ // pr b7 b6 b5 b4 b3 b2 b1 | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
+ // b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 XT_IBM-done ^2
+ // pr b7 b6 b5 b4 b3 b2 b1 | 1 0 *1 0 0 0 0 0 AT-midway[b0=1] ^2
+ // x x x x x x x x | x 1 1 0 0 0 0 0 illegal
+ // st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 AT-done
+ // x x x x x x x x | x x 1 *1 0 0 0 0 illegal
+ // all other states than above illegal
+ //
+ // ^1: AT and XT_IBM takes same state.
+ // ^2: AT and XT_IBM takes same state in case that AT b0 is 1,
+ // we have to check AT stop bit to discriminate between the two protocol.
+ switch (isr_state & 0xFF) {
+ case 0b00000000:
+ case 0b10000000:
+ case 0b01000000: // ^1
+ case 0b00100000:
+ // midway
+ goto NEXT;
break;
- case PARITY:
- if (dbit) {
- if (!(parity & 0x01))
- goto ERROR;
- } else {
- if (parity & 0x01)
- goto ERROR;
- }
+ case 0b11000000:
+ // XT_Clone-done
+ isr_state = isr_state>>8;
+ ibmpc_protocol = IBMPC_PROTOCOL_XT_CLONE;
+ goto DONE;
+ break;
+ case 0b10100000: // ^2
+ {
+ uint8_t us = 100;
+ // wait for rising and falling edge of AT stop bit to discriminate between XT and AT
+ while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
+ while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
+
+ if (us) {
+ // found stop bit: AT-midway - process the stop bit in next ISR
+ goto NEXT;
+ } else {
+ // no stop bit: XT_IBM-done
+ isr_state = isr_state>>8;
+ ibmpc_protocol = IBMPC_PROTOCOL_XT_IBM;
+ goto DONE;
+ }
+ }
break;
- case STOP:
- if (!dbit)
- goto ERROR;
- if (!ringbuf_put(&rb, data)) {
- ibmpc_error = IBMPC_ERR_FULL;
- goto ERROR;
- }
- ibmpc_error = IBMPC_ERR_NONE;
+ case 0b00010000:
+ case 0b10010000:
+ case 0b01010000:
+ case 0b11010000:
+ // AT-done
+ // TODO: parity check?
+ isr_state = isr_state>>6;
+ ibmpc_protocol = IBMPC_PROTOCOL_AT;
goto DONE;
break;
- default:
+ case 0b01100000:
+ case 0b11100000:
+ case 0b00110000:
+ case 0b10110000:
+ case 0b01110000:
+ case 0b11110000:
+ default: // xxxx_oooo(any 1 in low nibble)
+ // Illegal
+ ibmpc_error = IBMPC_ERR_ILLEGAL;
goto ERROR;
+ break;
}
- goto NEXT;
ERROR:
- ibmpc_error |= state;
- ibmpc_error |= IBMPC_ERR_RECV;
- ringbuf_reset(&rb);
-DONE:
- last_time = 0;
- state = START;
- data = 0;
- parity = 1;
+ isr_state = 0x8000;
+ recv_data = 0xFF00; // clear data and scancode of error 0x00
return;
+DONE:
+ if ((isr_state & 0x00FF) == 0x00FF) {
+ // receive error code 0xFF
+ ibmpc_error = IBMPC_ERR_FF;
+ }
+ if ((recv_data & 0xFF00) != 0xFF00) {
+ // buffer full and overwritten
+ ibmpc_error = IBMPC_ERR_FULL;
+ }
+ recv_data = recv_data<<8;
+ recv_data |= isr_state & 0xFF;
+ isr_state = 0x8000; // clear to next data
NEXT:
- state++;
return;
}
projects / max / tmk_keyboard.git / blobdiff