SPI MOSI Voltage Level and No gap between bytes

Cd4768gg
Posts: 18
Joined: Wed Apr 27, 2022 7:07 pm

SPI MOSI Voltage Level and No gap between bytes

Postby Cd4768gg » Thu May 26, 2022 11:49 pm

Hello,

I am sending out FF FF FF
but there is no gap between the 3 bytes
and the voltage level of MOSI is only about 1.5V compared to the chip select and clock ~3.3V
(ref attached ESP.png)
Chip Select Yellow, Clock Blue, MOSI Pink

How do I get the MOSI level to be around 3.3V
How did I insert a gap between the bytes, for example the aardvark SPI host adapter I have looks to put a byte of no clock and no MOSI between bytes (ref attached Aardvark.jpg)

Thank you
Chris
Attachments
Aardvark.jpg
Aardvark.jpg (88.84 KiB) Viewed 1329 times
ESP.png
ESP.png (20.03 KiB) Viewed 1329 times

Cd4768gg
Posts: 18
Joined: Wed Apr 27, 2022 7:07 pm

Re: SPI MOSI Voltage Level and No gap between bytes

Postby Cd4768gg » Thu May 26, 2022 11:52 pm

sorry, I attached the wrong ESP image, please disregard the ESP.png in the original post and reference the attached ESP2.png
Attachments
ESP2.png
ESP2.png (19.88 KiB) Viewed 1324 times

Cd4768gg
Posts: 18
Joined: Wed Apr 27, 2022 7:07 pm

Re: SPI MOSI Voltage Level and No gap between bytes

Postby Cd4768gg » Thu May 26, 2022 11:53 pm

also the aardvark is sending AA AA instead of FF FF FF

ESP_Sprite
Posts: 8926
Joined: Thu Nov 26, 2015 4:08 am

Re: SPI MOSI Voltage Level and No gap between bytes

Postby ESP_Sprite » Fri May 27, 2022 12:46 am

SPI doesn't have a concept of bytes; there's no reason why the ESP would not send it out as one continuous stream, and unless you have a very odd device on the other side of the bus, it should not require a delay between each 8 SPI clock cycles.

Wrt the 1.8V MOSI: What hardware are you using (in case of a module: what module specifically) and what GPIOs do you use for the SPI bus? Could be that you have a module that uses an 1.8V flash; that also affects some other GPIOs (if memory serves, at least GPIO16 and 17)

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