Dear,
I am not sure whether it is a bug or me (most likely me though).
I use VS code and ESP-IDF 5.3.1. The board has an ESP32-S3 WROOM-1 on a DevKitC.
I use the SPI element in master mode. I want to send an 8-bit address and in response receive 8 bit data. I have used my 4-channel oscilloscope to debug my code. Thus, I know the ESP32-S3 sends 20 clock pulses while I had expected 16 only (and so has the slave). I have tried with SPI2_HOST and SPI3_HOST, but it makes no difference.
The clock rate is 1.0 MHz
The settings of the SPI are in the file attached. I have specifically specified no dummy bits and clock pulses.
Why does the ESP32-S3 send 20 clock pulses?
Which of my settings is wrong?
Is it a bug or is it me?
Regards,
Jorgen
SPI 20 clock pulses when 16 were expected
SPI 20 clock pulses when 16 were expected
- Attachments
-
- SPI.txt
- (1.44 KiB) Downloaded 74 times
Re: SPI 20 clock pulses when 16 were expected
Using an oscilloscope reveals the 20 clock pulses are 4 + 16 i.e. there are 4 clock pulses send before the content of the 8-bit address.
I have modified my code to use full duplex. In that case only 16 clock pulses are sent. That is a solution for me, but I would still appreciate receiving instructions on how to use half duplex and 16 pulses only (8 pulses for the 8-bit address and 8 for the 8-bit data.
Regards,
Jorgen
I have modified my code to use full duplex. In that case only 16 clock pulses are sent. That is a solution for me, but I would still appreciate receiving instructions on how to use half duplex and 16 pulses only (8 pulses for the 8-bit address and 8 for the 8-bit data.
Regards,
Jorgen
Re: SPI 20 clock pulses when 16 were expected
I have found the error.
I have used as flag SPI_DEVICE_NO_DUMMY within the transaction_t structure. That is wrong. That flag belongs in the spi_device_interface_config_t structure. I have moved it there and now 16 clock pulses are sent only.
The subject is closed.
Sorry for any inconvenience.
Regards,
Jorgen
I have used as flag SPI_DEVICE_NO_DUMMY within the transaction_t structure. That is wrong. That flag belongs in the spi_device_interface_config_t structure. I have moved it there and now 16 clock pulses are sent only.
The subject is closed.
Sorry for any inconvenience.
Regards,
Jorgen
-
- Posts: 9708
- Joined: Thu Nov 26, 2015 4:08 am
Re: SPI 20 clock pulses when 16 were expected
Glad you managed to find the issue!
Who is online
Users browsing this forum: No registered users and 39 guests