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MCG->C7 generated by Expert Config tool for K20, doesn't exist: workaround??

Question asked by Robert Lewis on Apr 14, 2017

I have found my build from the Clock generator is crashing after generating the clock.c code with the off-line Expert Configuration tool. A value is being set in MCG->C7, in fsl_clock.c, however there is NO C7 in the MCG for the K20dx256ZVLL10.

This is on the MK20DX256ZVLL10, and the MK60DN512VLL10 the clock generation tool with SDK2.2 is generating/using code in the fsl_clock.c module with the call below

status_t CLOCK_SetExternalRefClkConfig(mcg_oscsel_t oscsel)

that accesses MCG->C7, however there is no MCG->C7


which then results in a hard fault. If I comment out the line
//**rwl MCG->C7 = (MCG->C7 & ~MCG_C7_OSCSEL_MASK) | MCG_C7_OSCSEL(oscsel);
there is no trap, but the system hangs at

(MCG_S_IREFST(kMCG_FllSrcExternal) | MCG_S_CLKST(kMCG_ClkOutStatExt)))


I can comment this out and manually configure the clocks but the next time the generator is run it will overwrite the code. Is this a problem with the generator, or the SDK 2.2 (freertos, usb, fat)?


Does anyone know a workaround, or perhaps I am not doing something correct. There are no errors in the Diagram or the output HTML configuration.


Any advice would be greatly appreciated.