Schematic update

Arduino compass toy:

I have had a little time to play with the OLED panel this week. Unfortunately, I still can’t get it to work.  I have been trying to get it to work in SPI mode, But I think I now want to try to start working in either 8080 or 6800 modes.

Schematic Update:

I updated the schematic to reflect the results of my testing from 2 weeks ago.

I still need to try a high gain transistor in place of the one I used to see what will happen.

I am waiting to make some decisions before I update the schematic on GitHub.

Decisions:

I am still trying to decide what the target interface should look like.  With the recent changes, I only have 5 data lines I can connect to the target device.  I have decided to leave the flash SPI unconnected.  This leaves the HSPI port (4 wires), plus GPIO16.  GPIO0 is only used for updating firmware in the ESP8266.  I could use it to give me one more data line.

I still need to decide if I am going to use the 8 Bit Level shifter, maybe just three 2 bit level shifters.  I have an Idea where the data direction control pins will be controlled by the target adapter.  If I stay with the current level shifter, I have to put pullups on the target data lines.

Looking Ahead:

Research is a big part of what is ahead.  I need to do some more testing with the Vpp circuit. I need a better understanding of target programming interfaces as well as JTAG interfaces. I still have some decisions to make before I change the layout.

Feedback:

As always, I’d love to hear from you.  I rarely get anything other than SPAM comments.  Do you see any advantages/disadvantages to going to 2 bit level shifters?  I’d love to hear about your projects.

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