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document usart RX FIFO

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Philippe Teuwen 2019-04-21 13:19:35 +02:00
parent 06cb40afbd
commit f8de50f5c9
1 changed files with 33 additions and 4 deletions
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doc/new_frame_format.txt
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@ -133,14 +133,11 @@ On the Proxmark3, for receiving frames:
*****************************************
PacketCommandNG
*****************************************
AppMain calls receive_ng(common/cmd.c) which calls usb_read_ng to get a PacketCommandNG, then passes it to PacketReceived.
AppMain calls receive_ng(common/cmd.c) which calls usb_read_ng/usart_read_ng to get a PacketCommandNG, then passes it to PacketReceived.
(no matter if it's an old frame or a new frame, check PacketCommandNG "ng" field to know if there are oldargs)
PacketReceive is the commands broker.
Old handlers will still find their stuff in "oldarg" field.
TODO AppMain still calls directly usart_readbuffer for USART and does not support new frames on USART.
On the Proxmark3, for sending frames:
-------------------------------------
(common/cmd.c)
@ -192,7 +189,39 @@ TODO
We need to be very careful to make a flasher that can deal with old & new bootroms.
New bootrom might need to also still support old frame format, to ease flashing back to repos supporting the old format...
New usart RX FIFO
=================
USART code has been rewritten to cope with unknown size packets.
* using USART full duplex with double DMA buffer on RX & TX
* using internal FIFO for RX
usart_init:
* USART is activated all way long from usart_init(), no need to touch it in RX/TX routines: pUS1->US_PTCR = AT91C_PDC_RXTEN | AT91C_PDC_TXTEN
usart_writebuffer:
* still using double DMA but accepts arbitrary packet sizes
* removed unneeded memcpy.
* wait for both DMA buffers to be treated before returning (TODO still needed?)
usart_read_ng:
* user tells expected packet length
* relies on usart_rxdata_available to know if there is data in our FIFO buffer
* fetches data from our FIFO
* dynamic number of tries (depending on FPC speed) to wait for asked data
usart_rxdata_available:
* polls usart_fill_rxfifo
* returns number of bytes available in our FIFO
usart_fill_rxfifo:
* if next DMA buffer got moved to current buffer (US_RNCR == 0), it means one DMA buffer is full
* transfer current DMA buffer data to our FIFO
* swap to the other DMA buffer
* provide the emptied DMA buffer as next DMA buffer
* if current DMA buffer is partially filled
* transfer available data to our FIFO
* remember how many bytes we already copied to our FIFO
Timings
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