TMS570LC4357: TMS570LC4357: Write to SPI flash using DMA Clarification regarding DMA control packet updates without disabling DMA controller

Hi Philippe,

We started working on your issue and we will provide an update soon.

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Thanks & regards,
Jagadish.

Hi Philippe,

If i understand correctly

You connected two SPI slave devices i.e. ADC and Flash to the single instance of SPI master of the controller with two different chip selects right? Something like below

If it is the case, how would you lost ADC data, anyway you have to disable the ADC slave CS and should need to enable the Flash chip to communicate with serial flash. And SPI slave it self can't send any data to the master until CS and clock are provided by master and master should send some dummy data to the slave to receive the data from slave device, so in this case if we disable the ADC chip select ADC cannot send any data until master finishes its communication with flash device right. After reenabling ADC chip select and providing clock only ADC acquisition data should receive by SPI master, If this is the scenario then there won't be any problem in disabling the DMA before reconfiguring the control packet.

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Thanks & regards,
Jagadish.

Hello Jagadish,

Our flash and ADC are on 2 different buses.

Currently, when we want to write to flash, we are disabling DMA before configuring a new DMA transfert and re-enabling DMA again.

The only issue is that while we are configuring DMA transfer for flash writing, we are stopping ADC acquisition.
You are right that last sample is not "lost" and still in ADC buffer, ready to be read our next SPI request.
However, we need to make periodic samples at a high frequency, and we would like that flash writing has no impact on other operations, avoid to introduce sampling delays.

So we would prefer to keep DMA enabled.
We are interested to know if there are any solution that would allow to keep DMA running on other peripherals, while we are configuring a new packet to write to flash.