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GPIO DMA transfer for slave port, input only | Cypress Semiconductor

GPIO DMA transfer for slave port, input only

Summary: 0 Replies, Latest post by Wavelength on 19 Dec 2011 12:36 PM PST
Verified Answers: 0
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Wavelength's picture
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I need to make a slave port, wereby the master (in this case PC/Linux) sends data (8 or 16, more later) to the PSOC3 which then streams this out I2S to a dac chip.

This PC/Linux machine has 2 ports available for me to do this:

1) IDE 16 bit parallel interface

2) Parallel Port with ECP/EPP capabilities

For ease of making this work, I am considering the ECP/EPP port since it is 8 bits wide and in ECP has DMA capabilities. The IDE works so similar so really here goes.

On a Write sequence to the PSOC3 there will be the following hardware setup (copied from    timming diagram there also):

1. Data is placed on Data lines by Host.
2. Host then indicates a Data Cycle will proceed by asserting HostAck.
3. Host indicates valid data by asserting HostClk low.
4. Peripheral sends its acknowledgment of valid data by asserting PeriphAck.
5. Host de-asserts HostClk high. +ve edge used to shift data into the Peripheral.
6. Peripheral sends it's acknowledgment of the byte via de-asserting PeriphAck.


Ok so say I transfer 512 bytes from the PC/Linux to the PSOC3. The problem I see is how do I know when the DMA transfer of each byte is done so I can indicate to the ECP port PeriphAck?

So I use the HostClk to indicate to the DMA that a transfer is required. But when do I know it read the port?

Same true with IDE if DMA or FIFO mode is used, how do I know the DMA read the port?

Or do I have to use the PLD functions to do this, some sort of latching then read?

Or is there some better way that I am missing?



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