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STM32F4 DMA REQ and ACK for External DMA

Question asked by Zaher on Oct 21, 2017
Latest reply on Oct 21, 2017 by Zaher

I'm trying to interface my STM32F407 MCU with a peripheral device that has independent DMA/MPU interfaces. The MPU interface is available in two modes (68 and 80) and the data bus width is available in 8-bit and 16-bit mode. The device can be configured to use the same bus for both of the DMA and the MPU, which I believe makes it easier to access the device utilizing the FSMC peripheral.


As far as the MPU interface is concerned, I'm not sure which mode works better in this situation as I did not try it yet (Muxed PSRAM vs LCD Interface), but seems like the LCD Interface is the way to go. 


My problem is how to adapt the REQ and ACK signals of the DMA controller on the peripheral chip while the STM32F4 maps requests only from internal peripheral of the MCU itself? Is this something ST has not taken into consideration for their Cortex-M devices? 


Any ideas?