8 bit Co-processor Research

Seeed Studio:

Seeed Studio has asked that I put a link to their site on this blog.  I have used Seeed Studio Fusion service and I was/am satisfied with them. So I have added a link in the right hand column.

This Week:

I decided to research potential processors for the level converter circuit.

Wikipedia has a list of common microcontrollers. This is a good resource when looking for possibilities.  I will only look at a few processors from companies I am familiar with. If this co-processor chip is going to act as a level shifter, It needs to be able to drive and accept 5 Volts.


ST Microelectronics makes STM8 and STM32 lines of processors. I will look at the STM32 line next week when I research 32 bit controllers.

The STM8 line has many processors that have a max operating voltage of 5.5 Volts.  Of the processors that can operate at 5.5 Volts, the lowest operating voltage is 2.95 volts.  This might be high for some ARM systems I would want to support.  ST Microelectronics supports their devices very well on Mac and Windows.  There is a good open source compiler available for Linux called Small Device C Compiler(SDCC). The STM8 line of chips doesn’t have any built in USB capabilities. The STM8 is a possibility.


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Side Project:

I played with the OLED display this week. With the data I have on the display that makes any sense, it should be working.  I received sample code from the distributor I bought the display from.  I modified it to work on arduino, and still no display.  I may have damaged my display while probing the signals.  I shorted Vdd to Vcc with my scope probe.  I saw a little spark and I was no longer getting 13 Volts on Vcc

Included with the sample code is a schematic that has a drop down voltage regulator on it to drive Vcc.  The drop down voltage regulator is configured to regulate to 6 Volts. However, the input to the drop down regulator is Vdd. According to the SSD1332 data sheet, Vdd should not exceed 3.6 Volts.  This suggests that I have incomplete information.  The datasheet also says that Vcc should be between 7 and 20 Volts.

I am thinking I will disable the switching regulator and do further testing while sending individual commands.  I think I might try one of the 8 bit interfaces to see if I can write to and read from RAM. That will confirm the data interface is wired correctly.

Port Expander vs Level Shifter:

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Refactoring Electronics (Hardware V00K)

Side Project:

I still haven’t gotten the OLED display working.  I am beginning to question Pinouts and even if the driver IC listed by the seller(s) is correct.  At this point I can’t even tell if the device is seeing my commands. I checked the board for shorts/solder bridges and even replaced the OLED display. I still can’t get anything to show up on the display.

I think a reasonable test would be to measure current to the display and send it a power on command.  If I am sending commands correctly, I should see a change in current draw.  After that, I will try working through the commands available in the datasheet for a SSD1332 chip looking for a change in the display or the current draw.


Just like refactoring the code, It’s time to refactor the electronics design.  I checked on my feature request on the Espressif forum. Nothing new has happened.  So I am considering adding an external ADC to measure voltages.

Planning and Research:

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