/*
-Copyright 2011 Jun WAKO <wakojun@gmail.com>
+Copyright 2011-19 Jun WAKO <wakojun@gmail.com>
Copyright 2013 Shay Green <gblargg@gmail.com>
This software is licensed with a Modified BSD License.
attention();
send_byte((addr<<4) | ADB_CMD_TALK | reg);
place_bit0(); // Stopbit(0)
+ // TODO: Service Request(Srq):
+ // Device holds low part of comannd stopbit for 140-260us
+ //
+ // Command:
+ // ......._ ______________________ ___ ............_ -------
+ // | | | | | | |
+ // Command | | | | | Data bytes | |
+ // ........|___| | 140-260 |__| |_............|___|
+ // |stop0 | Tlt Stop-to-Start |start1| |stop0 |
+ //
+ // Command without data:
+ // ......._ __________________________
+ // | |
+ // Command | |
+ // ........|___| | 140-260 |
+ // |stop0 | Tlt Stop-to-Start |
+ //
+ // Service Request:
+ // ......._ ______ ___ ............_ -------
+ // | 140-260 | | | | | |
+ // Command | Service Request | | | | Data bytes | |
+ // ........|___________________| |__| |_............|___|
+ // |stop0 | |start1| |stop0 |
+ // ......._ __________
+ // | 140-260 |
+ // Command | Service Request |
+ // ........|___________________|
+ // |stop0 |
+ // This can be happened?
+ // ......._ ______________________ ___ ............_ -----
+ // | | | | | | 140-260 |
+ // Command | | | | | Data bytes | Service Request |
+ // ........|___| | 140-260 |__| |_............|_________________|
+ // |stop0 | Tlt Stop-to-Start |start1| |stop0 |
+ //
+ // "Service requests are issued by the devices during a very specific time at the
+ // end of the reception of the command packet.
+ // If a device in need of service issues a service request, it must do so within
+ // the 65 µs of the Stop Bit’s low time and maintain the line low for a total of 300 µs."
+ //
+ // "A device sends a Service Request signal by holding the bus low during the low
+ // portion of the stop bit of any command or data transaction. The device must lengthen
+ // the stop by a minimum of 140 J.lS beyond its normal duration, as shown in Figure 8-15."
+ // http://ww1.microchip.com/downloads/en/AppNotes/00591b.pdf
if (!wait_data_hi(500)) { // Service Request(310us Adjustable Keyboard): just ignored
+ xprintf("R");
sei();
- return -30; // something wrong
+ return 0;
}
if (!wait_data_lo(500)) { // Tlt/Stop to Start(140-260us)
sei();
- return 0; // No data to send
+ return 0; // No data from device(not error);
}
// start bit(1)
- if (!wait_data_hi(40)) return 0;
- if (!wait_data_lo(100)) return 0;
+ if (!wait_data_hi(40)) {
+ xprintf("S");
+ sei();
+ return 0;
+ }
+ if (!wait_data_lo(100)) {
+ xprintf("s");
+ sei();
+ return 0;
+ }
uint8_t n = 0; // bit count
do {
uint8_t hi = (uint8_t) wait_data_lo(lo);
if (!hi)
- goto error; // stop bit extedned by Srq
+ goto error; // stop bit extedned by Srq?
if (n/8 >= len) continue; // can't store in buf
attention();
send_byte((addr<<4) | ADB_CMD_LISTEN | reg);
place_bit0(); // Stopbit(0)
+ // TODO: Service Request
_delay_us(200); // Tlt/Stop to Start
place_bit1(); // Startbit(1)
for (int8_t i = 0; i < len; i++) {