Fix hexpansions not being consistently detected on hotplug #122
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For mysterious reasons the GPIO expanders seem to not always update the state of port 1 when doing a multi-byte read. If we instead do two single-byte reads, we appear to get the correct state 100% of the time. The datasheet has some confusing lines about how you always need to send a write command before reading the port states - I believe readfrom_mem actually does this, but since it's not actually sending any data for the write, it's only technically writing to address 0, which only updates port 0 (hence why buttons work consistently - they're all port 0!)
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... fixes #89 ? |
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I suspect this is also needed for set_egpio_pin. Writing the the LS pins through the badge code doesn't work on some hexpansions - likely also where the pins are on port 1. Whereas code writing only one byte (port) at a time is fine. |
Previous code was only writing to one expander & may have suffered from the multi-byte read bug
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Pushed an extra commit to fix |
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Tested on a badge with dodgy hexpansion finding - works for me |
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For mysterious reasons the GPIO expanders seem to not always update the state of port 1 when doing a multi-byte read. If we instead do two single-byte reads, we appear to get the correct state 100% of the time.
The datasheet has some confusing lines about how you always need to send a write command before reading the port states - I believe
readfrom_memactually does this, but since it's not actually sending any data for the write, it's only technically writing to address 0, which only updates port 0 (hence why buttons work consistently - they're all port 0!)Fixes #89