I am attempting to load a custom OS from SDcard. I have a SDCard boot loader that uses the IVT etc to initialise the dram, then load a kernel at 0x17800000 in dram.
If I paste a linux kernel on the end of this it runs, so I know ram is set up and the kernel is put in the right place to execute.
I then put my minimal kernel in place of the linux kernel and see nothing.
I am attempting to send something via the serial port but must be missing something.
What I do is:
1: set AIPS1_MPR0to7 and 8to15 to 0x77777777 to turn on unbuffered write access to all masters. the same for AIPS2
2: set all the AIPSx_OPACR registers to 0 to unbuffered un priveledged write to all peripherals
3: set pads PAD_CTL for _EIM_D19/20 and CSI0_DAT10/11 to 0x1b0b0 (the 4 pins in use
4: set MUX_CTL for CSI0_DAT10/11 to 3 (alt_3)
5: set UART1_IPP_UART_RXD and UART_RTS_B to 1
6: clear bottom 6 bits of CCM_CSCDR1 to set uartpodf divider to 1
7: set CCM_CCGR5 bits 24-27 to enable uart clocks
8: usual uart setup, with known working routines.
What have I missed??? I cannot get any toggling of serial output pin
THanks in hope