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OnionIoT / i2c-exp-driver

Driver to program I2C based Onion Expansions
GNU Affero General Public License v3.0
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setCursor() function in Python module returns "I2C transaction failed." #21

Open impactful opened 6 years ago

impactful commented 6 years ago

After installing gcc, make, git, and python-dev on Omega2+ booting from SD card, the Python "setCursor()" function fails, with the following message:

IOError: I2C transaction failed.

The command-line and C versions set row correctly, but not column. No error is returned.

greenbreakfast commented 6 years ago

what column are you trying to set the cursor to? have you seen the set column addressing functions? https://docs.onion.io/omega2-docs/oled-expansion-python-module.html#oled-py-set-column-addressing

impactful commented 6 years ago

I have not changed column addressing values from defaults (0 and 127).

At the command line, a concatenated oled-exp command works:

oled-exp cursor 3,0 write "How are you?"

But, issuing two consecutive commands:

oled-exp cursor 3,0 oled-exp write "How are you?"

...results in writing starting on the first column.

I'm not sure how to handle this in Python or C.

My work-around has been to issue I2C commands directly. In Python, this works:

i2c.writeBytes(0x3C, 0x80, 0xB0) sets cursor to beginning of row 0. i2c.writeBytes(0x3C, 0x80, 0xB1) sets cursor to beginning of row 1. etc.

greenbreakfast commented 6 years ago

The oled-exp write "How are you?" command will reset the cursor to the very first column. Ok, we'll put this on the list of things to debug!