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Electronics => Beginners => Topic started by: Sarcarean on October 14, 2018, 10:07:38 am

Title: Single-Wire EEPROM Implementation Problem (AT21CS11)
Post by: Sarcarean on October 14, 2018, 10:07:38 am
So I am banging my head against the keyboard now. I am trying to read a SWI EEPROM (AT21CS11) using PB7 of ATMEGA32U2. I have that line connected to VCC (3.3V) with a 2K  \$\Omega\$ resistor. I am not sure what the problem is, but I have noticed that the reset and discover event does not look correct.

The RESET and DISCOVER event should look like this: PB7_LOW, wait 200uS, PB7_Release, wait 10uS, PB7_LOW, wait 1uS and release, then check if bus is being pulled down by AT21.

Here is what the correct waveform looks like:
(https://www.embeddedcomputers.net/images/swi_correct.png)

However, here is what mine looks like:
(https://www.embeddedcomputers.net/images/swi_incorrect.png)

Does anyone have any ideas of what I did wrong?