[Owfs-developers] Non related OWFS help with 1-Wire devices.

[Henrik Ö. <tr...@gm...>]

Hi!
I have been following the OWFS project for 20+ years and I really think
it's a marvelous piece of software. It's been run on a Raspberry Pi for
many years now to control the heating in our house.
However lately my Raspberry Pi has been more and more unstable,
overheating problems, diskfailure, hanging, owserver unexpectedly going
down and soo forth. It really got me thinking if my setup is the best
approche, my wife and kids should not have to be Unix admins and be able to
SSH to my server and restart the Docker container with Owserver just to not
freeze when I'm out on a business trip! So in a true Unix spirit I'm
splitting my Home automation system appart into well defined pieces that
"do one thing and do it well".
My house is heated by water-based floor heating, and there are three floor
heating control centers, with relays opening and closing the water-valves.
Each control center has a DS2408 controlling the relayes of 3-5 valves. A
made a small circuit board with a commonly used Arduino compatible
microcontroller that reads the temperature in the rooms using DS1820
sensors, then instructs the DS2408 to open/close the right valve. There is
one circuit board for each control center, so if one goes down only a few
rooms get affected. There is a reset-button on each circuit board that
could be used to restart it for whatever reason, and since there are no
filesystems mounted there is no problem with corruption in case of power
loss, and restarting only takes a second. The Raspberry Pi is now only used
for plotting graphs, MQTT and other home automation tasks.

Since I no longer use Owserver in my setup, I understand that it may be
inappropriate to ask for help within this forum. But I know that there are
some 10+ years skilled developers here with deep knowledge of 1-Wire
systems so I'm still going to pop the questions, maybe you could direct me
to a more suitable forum where we could continue the discussion?

 The problem I'm having is with the DS2408 devices, I only seem to be able
to communicate with them using the SKIP-ROM command, if I try to address
them individually then I only get garbage and errors back. The same code
works great when addressing DS2423 and DS18(B/S)20 devices, so I think the
code itself should work. Maybe I have missed something when communicating
or initializing the DS2408? I tried to read all the Maxim specs, and it
feels like I'm doing everything right. During startup I begin with
initializing the DS2408 and set the pins to output and to a known state.

void ds2408_reset(DS2480B &ds, onewireNode &node) {
ESP_LOGD(TAG, "Reset DS2408, id: %s.", node.idStr.c_str());
if (existTestMode(ds, node)) {
// Configure RSTZ as STRB output.
//ds.select(node.id); // reselect last selected device.
ds.write(SKIP_ROM); // HACK, this select all devices on the bus, but we
should select only this single device. Though I get CRC-errors using above
line.
ds.write(0xCC); // Issue Write Conditional Search Register command
ds.write(0x8D); // TA1, target address = 8Dh
ds.write(0x00); // TA2, target address = 008Dh
ds.write(0x04); // Write byte to Control/Status Register, RSTZ as STRB
output

// Verify configuration setting
if (!ds.reset()) {
ESP_LOGW(TAG, "Reset DS2408 failed after non-success configure RSTZ as
STRB.");
node.errors++;
return;
}

ds.write(RESUME); // reselect last selected device.
ds.write(0xF0); // Issue Read PIO Registers command
ds.write(0x8D); // TA1, target address = 8Dh
ds.write(0x00); // TA2, target address = 008Dh
auto status = ds.read(); // Read Control/Status Register and verify
ESP_LOGD(TAG, "DS2408 verify configuration setting: %s.", String(status, HEX
));

// Set all relays off.
setState(ds, node, B11111111);
} else {
ESP_LOGW(TAG, "Reset DS2408 failed for id: %s.", node.idStr.c_str());
}
}

/**
* Exit test-mode.
* "The DS2408 is sensitive to the power-on slew rate and can inadvertently
power up with a test mode
* feature enabled. When this occurs, the P0 port does not respond to the
Channel Access Write command."
* @return 0=failed, 1=success
*/
bool existTestMode(DS2480B &ds, onewireNode &node) {
// RST PD 96h <64-bit DS2408 ROM Code> 3Ch RST PD
if (ds.reset()) { // onewire initialization sequence, to be followed by
other commands
ds.write(0x96);
for (uint8_t i = 0; i < 8; i++) {
ds.write(node.id[i]);
}
ds.write(0x3C);

if (ds.reset()) {
return 1;
}
}

return 0;
}

int16_t setState(DS2480B &ds, onewireNode &node, uint8_t state) {
if (node.id[0] != DS2408) {
ESP_LOGW(TAG, "Device is not a DS2408!");
return -1;
}

if (ds.reset()) { // onewire initialization sequence, to be followed by
other commands
ESP_LOGD(TAG, "Set DS2408 state to: %s.", String(state, BIN));
uint8_t retries = MAX_CONSECUTIVE_RETRIES;
//ds.select(node.id); // issues onewire "MATCH ROM" address which selects a
SPECIFIC (only one) 1-Wire device
ds.write(SKIP_ROM); // HACK, this select all devices on the bus, but we
should select only this single device. Though I get CRC-errors using above
line.

do {
ds.write(0x5A); // Issue Channel-access Write command
ds.write(state); // Write byte to PIO
ds.write(~state); // Write inverted byte to PIO
auto status = ds.read(); // Read for verification (AAh = success)
auto newState = ds.read(); // DS2408 samples PIO pin status

if (status == 0xAA) { // AAh = success
ESP_LOGD(TAG, "DS2408 current state: %s.", String(newState, BIN));
node.success++;
return newState;
} else {
node.errors++;
ESP_LOGW(TAG, "DS2408 setState failed, trying again...");

if (ds.reset()) {
ds.write(RESUME); // reselect last selected device.
} else {
ESP_LOGW(TAG, "Reset DS2408 failed after non-success setState.");
node.errors++;
return -1;
}
}
} while (--retries);

return -1;
} else {
ESP_LOGW(TAG, "Reset DS2408 failed.");
node.errors++;
return -1;
}
}

When using "ds.select(node.id);" it does not work, with "ds.write(SKIP_ROM)
it works better, the question is why? And if it does matter, the
circuit-board is using a DS2480 to communicate with the other devices.

Any help or suggestions would be more than welcome!
Thanks!

// Henrik