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ds2408.c
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ds2408.c
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/*
* Copyright © 2010, Matthias Urlichs <[email protected]>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License (included; see the file LICENSE)
* for more details.
*/
/* This code implements (some of) the DS2408 8-bit I/O (obsolete).
*/
#include "features.h"
#include "onewire.h"
#define C_READ_PIO 0xF0
#define C_READ_CHANNEL 0xF5 // TODO
#define C_WRITE_CHANNEL 0x5A // TODO
#define C_WRITE_CONDSEARCH 0xCC // TODO
#define C_RESET_LATCHES 0xC3 // TODO
static u_char
pio_logic = 0xFF,
pio_output_latch = 0xFF,
pio_activity_latch = 0x00,
cond_search_mask = 0x00,
cond_polarity_mask = 0x00,
control_status = 0x88;
/*
The following code does:
* receive address (2 bytes), add them to CRC
* transmit anything from this address onwards until
0x8F is reached
* send the 2 crc bytes.
This is all very straightforward, except that the CRC calculation
for the first byte to transmit is delayed somewhat:
the time between recv_byte_in() and xmit_byte() is only a bit wide,
which may not be enough time to add a CRC byte.
*/
void do_read_pio(void)
{
u_short crc = 0;
u_short adr;
u_char bcrc = 1;
u_char b;
recv_byte();
crc = crc16(crc,0xF0);
b = recv_byte_in(); // address low byte
recv_byte();
crc = crc16(crc, b);
adr = b;
b = recv_byte_in(); // address high byte
adr |= b<<8;
/* note: bcrc is only true for the first byte to transmit */
#define XMIT(val) do { \
xmit_byte(val); \
if(bcrc) { crc = crc16(crc, b); bcrc = 0; } \
crc = crc16(crc,val); \
} while(0)
while(adr < 0x88) { XMIT(0); adr++; }
switch(adr) {
case 0x88: XMIT(pio_logic);
case 0x89: XMIT(pio_output_latch);
case 0x8A: XMIT(pio_activity_latch);
case 0x8B: XMIT(cond_search_mask);
case 0x8C: XMIT(cond_polarity_mask);
case 0x8D: XMIT(control_status);
case 0x8E: XMIT(0xFF);
case 0x8F: XMIT(0xFF);
crc = ~crc;
xmit_byte(crc);
xmit_byte(crc >> 8);
default:
while(1)
XMIT(0xFF);
}
}
void do_command(u_char cmd)
{
if(cmd == C_READ_PIO) {
DBG_P(":I");
do_read_pio();
} else {
DBG_P("?CI");
DBG_X(cmd);
set_idle();
}
}
void update_idle(u_char bits)
{
//DBG_C('\\');
uart_try_send();
}
void init_state(void)
{
}