Riva:
You will know if the data is correct if you never get UART framing errors.
I mentioned about the A/B high idle as adding a UART protocol decoder to the wrong one may cause wrong data values and framing errors to be returned in the decode data.
This is just the sort thing I like working on and even looks at the Vado unit for playing with but it would be too expensive for just the fun of it.
Had to put this down for a bit again as I've been really struggling with it.
When I use the RS485 modules I can't seem to replicate the unit's initial pattern in a sensible way. I set the baud to 9600 but when I send a character it's so much shorter than the pattern from the unit.
The only way I've managed to get close is with the following but it's not using the RS485 module at all so I don't think it'll work with the unit:
long unsigned lastCom = 0;
long unsigned curMicros = 0;
const int digPinHigh = 30;
const int digPinLow = 31;
const int byteLen = 7;
bool valArray[] = {HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH};
const int bitLen = 104;
const unsigned long comPeriod = 55000;
void setup() {
pinMode(digPinHigh, OUTPUT);
pinMode(digPinLow, OUTPUT);
digitalWrite(digPinHigh, LOW);
digitalWrite(digPinLow, HIGH);
}
void loop()
{
curMicros = micros();
if ((curMicros > (lastCom + comPeriod)) || (curMicros < lastCom)) {
lastCom = curMicros;
for (int j = 0; j < byteLen; ++j) {
for (int i = 0; i < sizeof(valArray); ++i) {
digitalWrite(digPinHigh, valArray[i]);
digitalWrite(digPinLow, valArray[i] == HIGH ? LOW : HIGH);
delayMicroseconds(bitLen);
}
digitalWrite(digPinHigh, LOW);
digitalWrite(digPinLow, HIGH);
delayMicroseconds(bitLen);
}
}
}
Monkey3:
When I use the RS485 modules I can't seem to replicate the unit's initial pattern in a sensible way. I set the baud to 9600 but when I send a character it's so much shorter than the pattern from the unit.
What if you use a lower baud rate, 300, 1200, 2400 and 4800 are standard rates below 9600 but it could also be custom.
Does your logic analyser protocol decoder have an auto baud option where it will try to figure out the baud rate for its self?
Riva:
What if you use a lower baud rate, 300, 1200, 2400 and 4800 are standard rates below 9600 but it could also be custom.
Does your logic analyser protocol decoder have an auto baud option where it will try to figure out the baud rate for its self?
Firstly, thank you Riva for your help on this. It's very much appreciated and is really keeping me invested.
ok, another step forwards perhaps...
I changed the arduino code that utlilises the rs485 module to the following:
long baudRate = 9600;
byte serialConfig = SERIAL_8N1;
#define TxControlMixer 3 //RS485 Direction control
#define RS485Transmit HIGH
#define RS485Receive LOW
long unsigned lastCom = 0;
long unsigned curMicros = 0;
const unsigned long comPeriod = 55000;
const int bitLen = 104;
byte message[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
void setup() {
Serial1.begin(baudRate, serialConfig);
// Init Transceiver
pinMode(TxControlMixer, OUTPUT);
digitalWrite(TxControlMixer, RS485Receive);
}
void loop()
{
curMicros = micros();
if ((curMicros > (lastCom + comPeriod)) || (curMicros < lastCom)){
lastCom = curMicros;
digitalWrite(TxControlMixer, RS485Transmit); // Enable RS485 Transmit
for (int i = 0; i < sizeof(message); ++i) {
Serial1.write(message[i]);
delayMicroseconds(bitLen);
}
}
}
The main point being I've removed the line that sets the RS485 module to receive. This means that the arduino is constantly in transmit which could be a problem when I connect the controller up but I'll get to that later.
This gave the right sort of pattern, as shown on the top line in the attached image.
Once I got to there I then changed the baud to 8750 (with some trial and error) which gave me the middle line.
The bottom line is the mixer.
Note:
the scale is not the same on each line
rather the measure at the top of each line shows the duration
So the overall length of a packet looks right but the individual segments look a little too short.
There are then a whole load of the following packet pairs are exchanged until the mixer has finished its start up (making whirring noises - to reset the proportioning valve I would guess):
If I press the power button, there's a bit of mess where it looks like the controller stops talking for a few packets while the mixer sends the following:
00 00 00 00 00 00 16
The controller then talks over the mixer for a couple of packets until it settles into the following:
00 00 00 00 00 00 16 12 72 01 16 07 02 00
After that I pressed the button to switch to a different shower outlet at which point there was some mess again followed by:
00 00 00 00 00 00 16 12 72 01 16 07 01 00
They then settled into the following:
00 00 00 00 00 00 16 11 72 01 16 07 01 00
I then hit the pause button, there was mess, then:
I'm sort of talking to the controller. Certainly it knows I'm talking and is responding.
I rewrote the code to replicate the 3 stage start up sequence (from post 21) and then connected the controller to the arduino and it seems to be responding.
As far as the data being received from the controller in response to the data I'm sending, it looks identical to what's received when it's connected to the arduino.
The only difference in the data, and the main issue I seem to be having, is that on one of the 2 rs485 data pins the idle is HIGH whereas on the mixer it's LOW (see attached).
I'd like to resolve the data issue in order to eliminate it from the investigation (plus I think the arduino's signal is wrong as per the rs485 spec / requirements / guidelines / whatever).
Aside from the data issue I've found that when I connect the controller to the arduino and power everything on, the screen stays on the "00", the backlight stays lit and the buttons are unresponsive.
However, if I start everything up and then move the controller connections to the mixer (which is powered on patiently waiting) the backlight then goes out which is the appropriate standby mode and the buttons are responsive.
Better yet, if I then move the connections back to the arduino, the buttons remain responsive. I can perform all of the usual actions on the buttons until I attempt to put it back into standby at which point the buttons then become unresponsive once more.
Clearly the unresponsive buttons is a blocker for real use but I may continue to work on the code that handles the state, temp, pressure, etc. until I have a breakthrough or somebody points out the glaringly obvious mistake to me...
Riva:
What RS485 module are you using and does it have the relevant/correct pullup/pulldown resistors on the A/B lines and maybe the 120 ohm terminator?
From the looks of the schematic it's got all the resistors and the board seems to match the schematic (in terms or the number of components).
My first thought was pull up / down resistors so I tried adding a couple of 220's in parallel (so 110 ohm) across the A / B and from each as pull up / down but all I managed to do was change the "incorrect" pin to the other one. So it feels like it's in the right region but I'm not really sure how to work out what's required.
The next thing I'm going to try is to measure the resistance across everything with the controller connected to the mixer and then again with the controller connected to the arduino, both with everything powered on and off.
At least that will tell me what the difference is between the 2 scenarios...
If you disconnect the mixer and just connect your logic analyser to A, B & Gnd of the MAX485 module while sending data, does it then show idle as low or still as high?
Riva:
If you disconnect the mixer and just connect your logic analyser to A, B & Gnd of the MAX485 module while sending data, does it then show idle as low or still as high?
That's strange, when TEST is low the MAX chip should be in receive mode and the pullup resistor should hold the A line high (on my image it is low but this is probably the logic probe pulling it down) and the pulldown holds the B line low. On your trace A is behaving as expected but B is remaining high.
I used a module that looks like yours but I don't have it with me to check the exact model and MAX chip used.
I'm at work and just happen to have a MAX485 chip (not module) to hand to connected it to using the same scheme and get the same results.
I've tried a second and third module and it's exactly the same (see attached) - although all the modules came in the same pack so that may be saying too much.
The chip is MAX485 ESA +18DN if that makes any difference.
When I look at your image versus mine, they look exactly the same but the mirror image.
With the exception that the test channel is not the mirror image.
I really don't know what that means.
I'm looking to see if there's another, different module I can get quickly and cheaply for comparison...
AFAIK the 3 characters after MAX485 denote the package type. ESA is 8 pin SO package.
When your testing you only have them connected to the logic analyser?
The Amazon link you posted has a schematic image so maybe check module matches schematic with a continuity meter
Maybe the whole packet of MAX485 modules are faulty or poorly designed/built or it could just be your logic device pulls the lines high when they are floating and mine pulls them low.
Riva:
AFAIK the 3 characters after MAX485 denote the package type. ESA is 8 pin SO package.
When your testing you only have them connected to the logic analyser?
The Amazon link you posted has a schematic image so maybe check module matches schematic with a continuity meter
Maybe the whole packet of MAX485 modules are faulty or poorly designed/built or it could just be your logic device pulls the lines high when they are floating and mine pulls them low.
When testing, I've tried a couple of different combinations and they all give the same result.
The new module doesn't have DE / RE pins, rather it relies on the TX to tell it when to switch to send / receive mode.
It does seem to properly switch back to idle though.
ALSO...
After some head bashing / panicking it would appear that actually the controller is working at 9600 baud with an ODD parity bit and I'm now able to immediately add a UART decoder with no frame errors!!!
It does mean that I now need to go back and re-analyse the mixer / controller traffic but that should be fairly easy.
Riva:
Glad you have one problem sorted and found the next hurdle to jump.
Just to put the old RS485 modules problem to bed how was you connecting them up?
For the old modules I connected them the same way described here.
Essentially:
Arduino
RS 485
TX
DI
RX
RO
3 (Direction Control)
DE / RE
GND
GND
5V
VCC
I don't know whether I got a bad batch or what but I must've re-wired the circuit about 50 times to make sure it was together correctly.
So gawd knows.