Blue F103ZET6 - PortB and EEPROM

Generic boards that are not Maple or Maple mini clones, and don't contain the additional USB reset hardware
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Pito
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Blue F103ZET6 - PortB and EEPROM

Post by Pito » Sun Jul 02, 2017 7:43 pm

Do you think the EEPROM below shall be removed from the board when running the PortB as 16bit TFT data bus?
The Blue F103ZET board has got the I2C EEPROM hardwired to the PortB.
F103ZET_EEPROM.JPG
F103ZET_EEPROM.JPG (27.23 KiB) Viewed 133 times
Last edited by Pito on Mon Jul 03, 2017 7:55 am, edited 1 time in total.
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ahull
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Re: F103ZET - PortB and EEPROM

Post by ahull » Sun Jul 02, 2017 10:45 pm

I suspect you would get away with not removing it, since the signals that will appear on the pins will look nothing like valid data to the eerom (and if they do, since you are not relying on the contents of the eerom, then if they get scrambled it doesn't matter).

There is a risk I suppose that the eerom may send data in response to some sequence on SCL (which might corrupt one bit of your 16bit bus).

If you could cut the track for -E and pull the EEROM enable pin high (it is active low), then you will disable the eerom without having to remove it. You could even tie the -E pin to another GPIO if you wanted to use the eerom, activating it only when the display is inactive.

Those two pullup resistor (R2, and R3) may cause issues, bit I suspect they wont.
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Pito
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Re: F103ZET - PortB and EEPROM

Post by Pito » Mon Jul 03, 2017 7:04 am

I've been running it wired, but I observe some artifacts and instability so it may come from there. I have to disable it.
I do not understand why the designers of these boards always introduce this kind of .... :(
Interestingly the W25X40 flash chip on the same board has got CS from portA and a 0ohm bridge in CS (the flash is also using portB signals) so it could be disabled easily..

The another issue is the 24C08N has a different wiring as shown in the schematics. With 24C08N only A2 is used for addressing. There is none E or CS there.

PS: maybe worth of mentioning it on our wiki - we talk this board http://wiki.stm32duino.com/index.php?ti ... 32F103ZET6
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