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Diffstat (limited to 'protocol/ibm4704.c')
| -rw-r--r-- | protocol/ibm4704.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/protocol/ibm4704.c b/protocol/ibm4704.c new file mode 100644 index 0000000000..10e229fd15 --- /dev/null +++ b/protocol/ibm4704.c @@ -0,0 +1,169 @@ +/* +Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com> +*/ +#include <stdbool.h> +#include <util/delay.h> +#include "debug.h" +#include "ibm4704.h" + + +#define WAIT(stat, us, err) do { \ + if (!wait_##stat(us)) { \ + ibm4704_error = err; \ + goto ERROR; \ + } \ +} while (0) + + +uint8_t ibm4704_error = 0; + + +void ibm4704_init(void) +{ + inhibit(); +} + +/* +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; + + /* 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); + //_delay_us(5); + 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); + + inhibit(); + _delay_us(200); // wait to recover clock to hi + return 0; +ERROR: + inhibit(); + if (ibm4704_error >= 0x30) { + xprintf("x%02X ", ibm4704_error); + } + _delay_us(200); // wait to recover clock to hi + return -1; +} + +/* receive data when host want else inhibit communication */ +uint8_t ibm4704_recv_response(void) +{ + // 250 * 100us(wait start bit in ibm4704_recv) + uint8_t data = 0; + uint8_t try = 250; + do { + data = ibm4704_recv(); + } while (try-- && ibm4704_error); + return data; +} + +/* +Keyboard to Host +---------------- +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 + +Start bit: can be long as 300-350us. +Inhibit: Pull Data line down to inhibit keyboard to send. +Timing: Host reads bit while Clock is hi. +Stop bit: Keyboard pulls down Data line to lo after 9th clock. +*/ +uint8_t ibm4704_recv(void) +{ + uint8_t data = 0; + bool parity = true; // odd parity + ibm4704_error = IBM4704_ERR_NONE; + + idle(); + _delay_us(5); // wait for line settles + + /* start bit */ + WAIT(clock_lo, 100, 0x11); // wait for keyboard to send + WAIT(data_hi, 100, 0x12); // can be delayed that long + + WAIT(clock_hi, 100, 0x13); // first rising edge which can take longer + /* data */ + for (uint8_t i = 0; i < 8; i++) { + WAIT(clock_hi, 100, 0x20+i); + //_delay_us(5); + if (data_in()) { + parity = !parity; + data |= (1<<i); + } + WAIT(clock_lo, 150, 0x28+i); + } + + /* parity */ + WAIT(clock_hi, 100, 0x17); + if (data_in() != parity) { + ibm4704_error = IBM4704_ERR_PARITY; + goto ERROR; + } + WAIT(clock_lo, 150, 0x18); + + /* stop bit */ + WAIT(clock_hi, 100, 0x19); + WAIT(data_lo, 1, 0x19); + + inhibit(); + _delay_us(200); // wait to recover clock to hi + return data; +ERROR: + if (ibm4704_error > 0x12) { + xprintf("x%02X ", ibm4704_error); + } + inhibit(); + _delay_us(200); // wait to recover clock to hi + return -1; +} |