Difference between revisions of "Talk:RPi GPIO Interface Circuits"
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--[[User:Dougbtv|Dougbtv]] ([[User talk:Dougbtv|talk]]) 20:43, 12 September 2013 (UTC) | --[[User:Dougbtv|Dougbtv]] ([[User talk:Dougbtv|talk]]) 20:43, 12 September 2013 (UTC) | ||
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| + | No, that's the way round I've got it. The diode is shifting the 0 and 3.3v from the Pi to ~0.7v and 4.0v at the ATMega's input pin. The data sheet gives the ATMega's VIH as 0.6Vcc, which is 3.0V when running from a 5V supply. This ought to 'just about work' but I found it was unreliable; possibly my wiring arrangements were rather noisy and the supply voltage was on the high side. Anyway, the diode shifter fixed it 100% for me. | ||
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| + | [[User:IanH|IanH]] ([[User talk:IanH|talk]]) 17:17, 17 March 2014 (UTC) | ||
Latest revision as of 10:17, 17 March 2014
Simple Diode Level converter --> Is the schematic backwards?
I kinda think has RxD & TxD transposed. The RxD on the ATMega should RECIEVE 3.3v OK, but, the RxD on the Raspberry pi needs the voltage drop from the diode.
Can someone confirm this? I'm a master of transposing these and making the same mistake myself, but... I'd appreciate the eyeballs. If someone can confirm what I see, I'll happily fix the file.
Thanks,
--Dougbtv (talk) 20:43, 12 September 2013 (UTC)
No, that's the way round I've got it. The diode is shifting the 0 and 3.3v from the Pi to ~0.7v and 4.0v at the ATMega's input pin. The data sheet gives the ATMega's VIH as 0.6Vcc, which is 3.0V when running from a 5V supply. This ought to 'just about work' but I found it was unreliable; possibly my wiring arrangements were rather noisy and the supply voltage was on the high side. Anyway, the diode shifter fixed it 100% for me.
