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git.gir.st - tmk_keyboard.git/blob - adb.c
2 #include <util/delay.h>
7 static inline void data_lo(void);
8 static inline void data_hi(void);
9 static inline bool data_in(void);
11 static inline void psw_lo(void);
12 static inline void psw_hi(void);
13 static inline bool psw_in(void);
16 static inline void attention(void);
17 static inline void place_bit0(void);
18 static inline void place_bit1(void);
19 static inline void send_byte(uint8_t data
);
20 static inline bool read_bit(void);
21 static inline uint8_t read_byte(void);
22 static inline uint8_t wait_data_lo(uint8_t us
);
23 static inline uint8_t wait_data_hi(uint8_t us
);
26 void adb_host_init(void)
35 bool adb_host_psw(void)
41 uint16_t adb_host_kbd_recv(void)
45 send_byte(0x2C); // Addr:2, Cmd:talk(11), Reg:0(00)
46 place_bit0(); // Stopbit
47 if (!wait_data_lo(0xFF)) // Stop to Start(140-260us)
48 return 0; // No data to send
49 if (!read_bit()) // Startbit(1)
52 data
= (data
<<8) | read_byte();
53 if (read_bit()) // Stopbit(0)
59 static inline void data_lo()
61 ADB_DDR
|= (1<<ADB_DATA_BIT
);
62 ADB_PORT
&= ~(1<<ADB_DATA_BIT
);
64 static inline void data_hi()
66 ADB_PORT
|= (1<<ADB_DATA_BIT
);
67 ADB_DDR
&= ~(1<<ADB_DATA_BIT
);
69 static inline bool data_in()
71 ADB_PORT
|= (1<<ADB_DATA_BIT
);
72 ADB_DDR
&= ~(1<<ADB_DATA_BIT
);
73 return ADB_PIN
&(1<<ADB_DATA_BIT
);
77 static inline void psw_lo()
79 ADB_DDR
|= (1<<ADB_PSW_BIT
);
80 ADB_PORT
&= ~(1<<ADB_PSW_BIT
);
82 static inline void psw_hi()
84 ADB_PORT
|= (1<<ADB_PSW_BIT
);
85 ADB_DDR
&= ~(1<<ADB_PSW_BIT
);
87 static inline bool psw_in()
89 ADB_PORT
|= (1<<ADB_PSW_BIT
);
90 ADB_DDR
&= ~(1<<ADB_PSW_BIT
);
91 return ADB_PIN
&(1<<ADB_PSW_BIT
);
95 static inline void attention(void)
102 static inline void place_bit0(void)
110 static inline void place_bit1(void)
118 static inline void send_byte(uint8_t data
)
120 for (int i
= 0; i
< 8; i
++) {
128 static inline bool read_bit(void)
138 // bit0 low time: 60-70% of bit cell(42-91us)
139 // bit1 low time: 30-40% of bit cell(21-52us)
140 // bit cell time: 70-130us
141 // [from Apple IIgs Hardware Reference Second Edition]
143 // After 55us if data line is low/high then bit is 0/1.
144 // Too simple to rely on?
146 wait_data_lo(75); // wait the beginning of bit cell
149 wait_data_hi(36); // wait high part of bit cell
153 static inline uint8_t read_byte(void)
156 for (int i
= 0; i
< 8; i
++) {
164 static inline uint8_t wait_data_lo(uint8_t us
)
166 while (data_in() && us
) {
173 static inline uint8_t wait_data_hi(uint8_t us
)
175 while (!data_in() && us
) {