I2C problem

Hi, i'm inexperienced with the Netduino platform but have some experience I2C.

 

Failing to get I2C up and running on my brand spanking new Netduino Plus 2, I try looking at the logic level.

 

Setup: A scope connected to "SD" and "SC" with a 4k7 pull up resistor connected to 3.3v rail.

 

Funny enough "SC" is around 1V constantly (odd value), while "SD" is at the expected 3.3v by default.

Could the problem be with the chip?

 

 

Regarding software, i have among others, tried to use: http://forums.netduino.com/index.php?/topic/563-i2cbus/#entry4156.

 

Heat: After a closer visual inspection, I noticed poor quality soldering on the top side of the enc28j60 and cortex chip that make it appear as if some pins could be shorted. A quick investigation with the old continuity checker did not support my suspicion. However, as both of the ships get rather hot I would like to know what normal idle temperatures could be, in order to rule out potentially malfunctioning chips.

 

The STM should run cool to the touch....If it gets warm/hot then its not happy///

Hi Delkrak,

What version of firmware are you using? Are you able to create a simple "blinking LED" program using the onboard LED? Can you drive the voltage of the I2C pins high/low using OutputPort?

Chris

The STM should run cool to the touch....If it gets warm/hot then its not happy///

Are you running it in a special power saving ect.?

I noticed that it does not get hot in bootloader mode, odd.

 

What version of firmware are you using? Are you able to create a simple "blinking LED" program using the onboard LED? Can you drive the voltage of the I2C pins high/low using OutputPort?

Firmware: 4.2.1.1 (currently)

I am able to change pin state off SDA, SCA and the LED. 

In addition, I am able to change the logic level of the pull down resistor using the OutputPort command.

The STM should not get hot at all...

Hi Delkrak,

The STM32F405 chips do get a bit warm (either by themselves or courtesy of heat dissipated throughout the PCB from LDO power regulators, etc.). If it feels hot then something is wrong. If it just feels warmer than the air conditioning...that's pretty normal (at least when the chip is running at 168MHz constantly).

On I2C: do you have a logic analyzer handy by any chance? If you can drive the pins high and low (using OutputPort) and read logic levels correctly with InputPort, then this is most likely not a hardware issue.

If it is a hardware issue and you picked up your Netduino in the last 30 days, we can arrange for a replacement We test each board pretty thoroughly before we ship them, though...so we hardly ever get RMAs.

Chris

Looks like this thread died, guess I have to buy a new one then.

 

Thanks for the help regardless of the outcome