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would it possible? #6

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werdegars opened this issue Nov 4, 2024 · 1 comment
Open

would it possible? #6

werdegars opened this issue Nov 4, 2024 · 1 comment

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@werdegars
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werdegars commented Nov 4, 2024

i have esp01 which have limited pins
but i2c pins is there
so i was thinking what if using PCF8574?
it expand the GPIO pins
and make PCD8544 to run behind PCF8574
woud it possible?
i have been searching PCD8544 lib but mostly using SPI connection

@mcauser
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mcauser commented Nov 4, 2024

The PCD8544 uses SPI to communicate.
The minimum pins you'll need are CLK, DIN and D/C.
CE and RST can be pulled low instead of using IOs.

The ESP-01 is very tight on pins. Any chance you can use one of the newer models with more pins broken out, eg ESP-12? Or an ESP32?

This guy had a crack at it. Not sure if it works. Looks like bit-banging SPI over the PCF8574 IO expander.
https://github.com/maxint-rd/I2C-PCF8574-PCD8544-Nokia-5110-LCD

If you could bit-bang SPI over an IO expander, then sure, could be possible. I've never tried it.
Refresh rate is going be be very slow compared to SPI. Like >20x slower.
Otherwise, theres I2C to SPI bridge chips, such as SC18IS606. Again, it's going to be slow, but should be achievable.

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