181 lines
3.6 KiB
C
181 lines
3.6 KiB
C
#include <stdbool.h>
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#include <util/delay.h>
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#include <avr/io.h>
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#include "adb.h"
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static inline void data_lo(void);
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static inline void data_hi(void);
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static inline bool data_in(void);
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#ifdef ADB_PSW_BIT
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static inline void psw_lo(void);
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static inline void psw_hi(void);
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static inline bool psw_in(void);
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#endif
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static inline void attention(void);
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static inline void place_bit0(void);
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static inline void place_bit1(void);
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static inline void send_byte(uint8_t data);
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static inline bool read_bit(void);
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static inline uint8_t read_byte(void);
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static inline uint8_t wait_data_lo(uint8_t us);
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static inline uint8_t wait_data_hi(uint8_t us);
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void adb_host_init(void)
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{
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data_hi();
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#ifdef ADB_PSW_BIT
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psw_hi();
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#endif
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}
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#ifdef ADB_PSW_BIT
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bool adb_host_psw(void)
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{
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return psw_in();
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}
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#endif
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uint16_t adb_host_kbd_recv(void)
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{
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uint16_t data = 0;
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attention();
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send_byte(0x2C); // Addr:2, Cmd:talk(11), Reg:0(00)
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place_bit0(); // Stopbit
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if (!wait_data_lo(0xFF)) // Stop to Start(140-260us)
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return 0; // No data to send
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if (!read_bit()) // Startbit(1)
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return -2;
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data = read_byte();
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data = (data<<8) | read_byte();
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if (read_bit()) // Stopbit(0)
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return -3;
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return data;
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}
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static inline void data_lo()
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{
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ADB_DDR |= (1<<ADB_DATA_BIT);
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ADB_PORT &= ~(1<<ADB_DATA_BIT);
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}
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static inline void data_hi()
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{
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ADB_PORT |= (1<<ADB_DATA_BIT);
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ADB_DDR &= ~(1<<ADB_DATA_BIT);
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}
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static inline bool data_in()
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{
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ADB_PORT |= (1<<ADB_DATA_BIT);
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ADB_DDR &= ~(1<<ADB_DATA_BIT);
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return ADB_PIN&(1<<ADB_DATA_BIT);
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}
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#ifdef ADB_PSW_BIT
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static inline void psw_lo()
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{
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ADB_DDR |= (1<<ADB_PSW_BIT);
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ADB_PORT &= ~(1<<ADB_PSW_BIT);
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}
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static inline void psw_hi()
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{
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ADB_PORT |= (1<<ADB_PSW_BIT);
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ADB_DDR &= ~(1<<ADB_PSW_BIT);
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}
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static inline bool psw_in()
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{
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ADB_PORT |= (1<<ADB_PSW_BIT);
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ADB_DDR &= ~(1<<ADB_PSW_BIT);
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return ADB_PIN&(1<<ADB_PSW_BIT);
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}
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#endif
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static inline void attention(void)
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{
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data_lo();
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_delay_us(700);
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place_bit1();
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}
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static inline void place_bit0(void)
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{
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data_lo();
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_delay_us(65);
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data_hi();
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_delay_us(35);
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}
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static inline void place_bit1(void)
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{
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data_lo();
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_delay_us(35);
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data_hi();
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_delay_us(65);
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}
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static inline void send_byte(uint8_t data)
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{
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for (int i = 0; i < 8; i++) {
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if (data&(0x80>>i))
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place_bit1();
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else
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place_bit0();
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}
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}
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static inline bool read_bit(void)
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{
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// ADB Bit Cells
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//
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// bit0: ______~~~
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// 65 :35us
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//
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// bit1: ___~~~~~~
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// 35 :65us
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//
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// bit0 low time: 60-70% of bit cell(42-91us)
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// bit1 low time: 30-40% of bit cell(21-52us)
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// bit cell time: 70-130us
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// [from Apple IIgs Hardware Reference Second Edition]
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//
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// After 55us if data line is low/high then bit is 0/1.
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// Too simple to rely on?
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bool bit;
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wait_data_lo(75); // wait the beginning of bit cell
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_delay_us(55);
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bit = data_in();
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wait_data_hi(36); // wait high part of bit cell
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return bit;
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}
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static inline uint8_t read_byte(void)
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{
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uint8_t data = 0;
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for (int i = 0; i < 8; i++) {
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data <<= 1;
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if (read_bit())
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data = data | 1;
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}
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return data;
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}
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static inline uint8_t wait_data_lo(uint8_t us)
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{
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while (data_in() && us) {
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_delay_us(1);
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us--;
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}
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return us;
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}
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static inline uint8_t wait_data_hi(uint8_t us)
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{
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while (!data_in() && us) {
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_delay_us(1);
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us--;
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}
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return us;
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}
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