HMC5883L Compass Module - Inverted Signal and Noise
geometrix
Posts: 27
All,
I recently purchased a Honeywell HMC5883L Compass Module from Parallax. I wrote some code in C programming language to interface with a Microchip PIC24F microcontroller. I have been seeing some strange behavior and I have somehow magically fixed the weird behavior.
The strange behavior included:
1. Inverted SCL and SDA lines on the I2C bus. I struggled with this for several hours. I finally walked away from my computer and just sat down to write this new thread....and the problem seems to have fixed itself! I have checked both CH1 and CH2 on my oscilliscope to confirm that they are NOT INVERTED. Any ideas why this might have happened???
2. Noise on the SCL and SDA lines upon release by the bus. So when the lines both go back to a HIGH state, I am seeing noise. I tried to use .1microFarad capacitors from the SCL pin to ground and from the SDA pin to ground...this did not solve the problem...seems to have "stretched" the signal with some other weird interaction.
The compass is equipped with the pull-ups that keep the SCL and SDA lines high when idle. How can I eliminate the noise???
TIA,
Neal
I recently purchased a Honeywell HMC5883L Compass Module from Parallax. I wrote some code in C programming language to interface with a Microchip PIC24F microcontroller. I have been seeing some strange behavior and I have somehow magically fixed the weird behavior.
The strange behavior included:
1. Inverted SCL and SDA lines on the I2C bus. I struggled with this for several hours. I finally walked away from my computer and just sat down to write this new thread....and the problem seems to have fixed itself! I have checked both CH1 and CH2 on my oscilliscope to confirm that they are NOT INVERTED. Any ideas why this might have happened???
2. Noise on the SCL and SDA lines upon release by the bus. So when the lines both go back to a HIGH state, I am seeing noise. I tried to use .1microFarad capacitors from the SCL pin to ground and from the SDA pin to ground...this did not solve the problem...seems to have "stretched" the signal with some other weird interaction.
The compass is equipped with the pull-ups that keep the SCL and SDA lines high when idle. How can I eliminate the noise???
TIA,
Neal