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unidirectional SPI configuration

Question asked by info@rwing.ch on Jun 29, 2020
Latest reply on Jul 1, 2020 by Felipe García

Hi

 

I have the LPCXpresso55S28 development board and want to control an OLED display with SPI interface (EA OLEDL128-6, controller SSD1309). The display can only receive data and not send. So I tried to use the SDK examples spi_interrupt and spi_dma_b2b_transfer_master. Both examples work with a master and a slave and I managed to get them working for some commands.

 

Beside sending data with DMA, I also tried to send data with the function SPI_WriteData. Unfortunately, after sending a particular amount of Instructions, no more data is sent. SSEL (D0) remains low and MOSI (D3) remains high. In the attached screenshot D2 is SCLK and D1 is RESET.

 

I'm quite sure that the reason is that I do not receive any data and the buffer is full after some instructions.

 

My questions are:

1) How can I configure the SPI interface as master only? According to the manual, RXIGNORE control bit can be used to avoid the need to read the received data. Can someone give me an example for a working configuration?
2) Does it make sense to use DMA when I do not receive any data? I think interrupt is the better way to go.

 

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