cooked eml327 ? After attempting to change the baud rate

[04colyZQ8]

I think I cooked my cheep eml327! it was working on baud 38400 cheap ford elmv1.2
<<at pp 0c sv 08 // set baud rate div 4000/8 = 500 k baud
>>ok
<< at pp 0c on
>>ok

that was the last time I could communicate with it tried 500000, 4800,9600,19200,38400,57600,115200,230400 no dice!!

took it apart traced pin 28 to led, hard reset force all pp to off, jumped to ground at obd 2 port and plugged into usb port, light blinked rapidly,

retry 500000, 4800,9600,19200,38400,57600,115200,230400 no dice!!

115200 sorta works bunk of fuzz and I do see v on the screen between fuzz after typing atz

Any suggestions??

[ironduke]

How are you connecting the elm? Bluetooth? Wi-Fi? USB? Serial?

If it’s a USB elm check the device manager and look at the com port and properties and settings to see if you can up the baud to 500k, see if the usb ti serial chip is even capable of that speed.

If it’s Bluetooth, not gonna be fixable unless you use another usb to serial adapter capable of 500k comms and wire it up bypassing the Bluetooth chip and set the baud rate back to normal.

Wi-Fi is probably gonna be the same as Bluetooth..

If it’s an actual old fashioned serial port elm then you just need to use a serial port capable of 500k speed..

The only other idea is on the genuine elm you could ground pin 6 and force 9600baud.. then you could change the speed back to normal and then reset and let pin 6 go back high.

By the way, if you can write any code above putty or a serial port program there are commands to try different speeds and see if they work, if they fail it reverts back to original speed..

[antus]

The divisor allows any speed, not just standard ones. And it may not be running standard hardware or clock. I'd say you've set a speed that isnt one of the normal ones that you have tried, and its save it to its own configuration. It is alive, the fuzz is data at the wrong speed. You might need to test more speeds, though there are a lot of them but you might get lucky. If you have a scope or a logic trace you could look at the timings on the wire and calculate the speed then set the pc to the same. But for the price of the elm clone unless you want to do it for interest sake its probably a better use of time to just bin it.

[04colyZQ8]

It’s usb hardwired.

I’m using putty it’s capable of 50000 but that’s not it.

It’s only showing fuzz from around 100000 to 120000

Randomly tried speeds between that especially close to 115200, no dice.

I wonder if I can write a program to continually very the speed in a loop checking for Elm327
Response If it contains Elm327 break, and print the baud rate that was used.

[04colyZQ8]

The divisor allows any speed, not just standard ones. And it may not be running standard hardware or clock. I'd say you've set a speed that isnt one of the normal ones that you have tried, and its save it to its own configuration. It is alive, the fuzz is data at the wrong speed. You might need to test more speeds, though there are a lot of them but you might get lucky. If you have a scope or a logic trace you could look at the timings on the wire and calculate the speed then set the pc to the same. But for the price of the elm clone unless you want to do it for interest sake its probably a better use of time to just bin it.

Dumb mistake I should have tried speed using at b , I think that is only temporary.

Because it’s not genuine elm327 that’s why the 28 pin reset isn’t quite working.

I used divisor 08.

If anyone has a knock off ford elm327 please read the pp settings.

At pps prints them.

I need to know what 0c was set at to obtain 38400 baud

Should be 68, 68 is 104 decimal.
4000/104= 38.4 baud

[04colyZQ8]

If it’s not 68, Maybe we can workout what speed I set this thing too!

[ironduke]

The problem is likely that the USB to serial chip isn't capable of 500k.. Check device manager and the USB to serial adapter properties and see if 500k is an option..

Also if you take it apart and ground pin 6 you should force 9600 baud. This would allow you to communicate and change pp 0c to something usable.. I know it's a knock off chip but see what pin 6 is connected to? If it's high try bringing it low with a 2k resistor or something.. Could try just shorting it out but I don't know what's bringing it high if it's connected in ckt..

from the elm327 data sheet..
Baud Rate (pin 6)
This input controls the baud rate of the RS232
interface. If it is at a high level during power-up or
reset, the baud rate will be set to 38400 (or the rate
that has been set by PP 0C). If at a low level, the
baud rate will be initialized to 9600 bps.

Every Elm327 I have screwed with has had the correct clock chip and the normal baud rate divisors..
I wrote some code awhile back with processing to connect and test and try 500k for some high speed can work and 2 out of 6 could do it..

[antus]

it might work, but most the elm clones now are allpro codebase hacked up with bits of it removed, or another codebase with different amounts of support for the elm command set and not running on the original pic mcu, and not with the original crystal speed. So absolutely try all this, but anything is possible with the hardware.

[04colyZQ8]

The problem is likely that the USB to serial chip isn't capable of 500k.. Check device manager and the USB to serial adapter properties and see if 500k is an option..

Also if you take it apart and ground pin 6 you should force 9600 baud. This would allow you to communicate and change pp 0c to something usable.. I know it's a knock off chip but see what pin 6 is connected to? If it's high try bringing it low with a 2k resistor or something.. Could try just shorting it out but I don't know what's bringing it high if it's connected in ckt..

from the elm327 data sheet..
Baud Rate (pin 6)
This input controls the baud rate of the RS232
interface. If it is at a high level during power-up or
reset, the baud rate will be set to 38400 (or the rate
that has been set by PP 0C). If at a low level, the
baud rate will be initialized to 9600 bps.



Every Elm327 I have screwed with has had the correct clock chip and the normal baud rate divisors..
I wrote some code awhile back with processing to connect and test and try 500k for some high speed can work and 2 out of 6 could do it..

Well I use a elm329 set at 500000 and it works with the same usb hub on my pc, newer gaming pc.

So I don’t think that’s an issue does only show 128000 as max under property’s

Seems it’s cooked grounded pin 6 then plugged in usb and release pin 6, no com at 9600.

[MudDuck514]

it might work, but most the elm clones now are allpro codebase hacked up with bits of it removed, or another codebase with different amounts of support for the elm command set and not running on the original pic mcu, and not with the original crystal speed. So absolutely try all this, but anything is possible with the hardware.

It was my understanding that the vast majority of the fake "ELM327" devices were using a hacked copy of V1.0 firmware (that was the original firmware, before the chips were read protected), and show V1.5,which was never an official release.
I don't see why someone COULDN'T be using something else though, so you may be right.

Mike