corrupt display on I2C display

Added by alan about 4 years ago

I have tested the display via the serial link and the test prog on the mbed. I get '0123456789abcdef' etc ok followed by key read:

however when i load the proper firmware ...
after the initial lines
I2c laser-panel

i get the a weird mix of texts inc the following
LO 03 ----- ----.
a 821 03:3org

a 821 03:3org

plus more of the same until the machine homes sucessfully
I can operate the buttons and scroll through more garbled screens and make the motors move etc so the display buttons seem to respond ok, its just the text makes no sense.
I can monitor via a terminal prog which confirms commands must be getting through.

Surely if there was a hardware problem the mbed test would fail?

I do only have a 128mb sd card though as all my others are greater then 2gb so could this be the problem?

thanks in advance!

Replies (2)

RE: corrupt display on I2C display - Added by Springuin about 4 years ago

I expect that there is something wrong with the I2C connection. Please check the connections and see if R7 and R8 on the mainboard are correct.
Also check the routing of the cable, not next to motor wires; the ground and 5V wire should be next to the SDA and SCL along the whole path.
If possible monitor the 5V wire with an oscilloscope or a multimeter to make sure it is a solid 5V all the time.

An 128MB SD card is fine. Note that on the rev5 board you need to use a normal size SD card holder or if you're using the micro sd holder you need to apply a patch.

RE: corrupt display on I2C display - Added by alan about 4 years ago

i eventually realised that the problem lay with the atmega 328 chip i was using or at least the firmware.
when I originally had difficluty in reprogramming my 168 chip, i purchased the 328 thinking it was compatible. I must have gone wrong somewhere along the line as it behaves strangely when in use but not when testing.

now I have (at last!) got my original chip reprogrammed all seems well.

When using the arduino software using a usb to ttl link, i set the board to ng or older but the chip options do not show an atmega 328 option, (only 168 or 8). but it lets me still upload the firmware ok. I don't know if this was the problem or not?
Anyway I'm happpy as all appears good!

thanks again