I'm looking at a BF549 via JTAG and trying to read out data manually from a NAND flash attached to the NFC but I never can get more than one byte out.
- reset board/processor
- disable interrupts
- configure portj fer & mux
- configure NFC_CTL
- W1C all NFC_IRQSTAT irq's to clear; NFC_IRQSTAT now 0x0
- try to do a READ_ID from the device with
NFC_CMD = 0x90
NFC_ADDR = 0x20
NFC_DATA_RD = xFF
read NFC_READ => 0x4F ; this correct, first byte of ONFI
NFC_IRQSTAT = 0x08 as expected (RD_RDY); but I cannot clear it with W1C's to this register
this kind of indicates the NFC doesn't believe I ever read the data, but clearly I did and got the right info. trying to process more bytes does not generate any additional read cycles to the NAND as you would expect with the stuck IRQ.
what am I missing? I have tried all kinds of memory access sizes for the registers and delays as well as two completely different technologies of jtag equipment & software.
I can't see how this could be related to anomaly 05000500.