I have an example program that uses the McBSP on an OMAP-L138 LCDK development board. When I run the program from within Code Composer and attempt to access the peripheral registers all I see is zeros. Also, if I try to modify any of the register values the updates are ignored and the register remains at zero. Looking at the full set of peripherals it seems that some are enabled and some are disabled. For example the REVID registers for some peripherals (e.g. UART0 and UART1) shows zero whereas others (e.g. UART2) show what looks like a sensible REVID value.
I had guessed that this might be to do with power domains or clock sources or some other initial configuration of the device. However, this does not seem to make sense as there are peripherals which share the same power domains and clock sources where some are 'enabled' and others are 'disabled'.
Is there a simple explanation and 'fix' for whatever is happening here to allow examining and changing the peripheal registers from the debugger?
'enabled' peripherals:
SYSCFG, UART2, I2C0, TIMER64*, SPI1, RTC, PLL*, GPIO, DDR2, MMCSD0, EMIF, EMAC, ECTL, MDIO, PSC*, SYSCFG
'disabled' peripherals:
EDMA, UART0, UART1, I2C1, HPIO, SPIO0, ECAP, EPWM, LCD, MMCSD1, USB, MCASP, MCBSP*, UPP*, VPIF, SATA