topic Re: CLKOUT in MK70F150 at PTA6 in Kinetis Microcontrollers

CLKOUT in MK70F150 at PTA6

dgalbarra — Thu, 28 Jul 2016 12:46:10 GMT

Hi all

According to Reference Manual, CLKOUT signal should be available at PTA6 pin, using Alt5 Mux configuration.

However, I can't see this signal in this pin. We have developed hardware with FlexBus access to external FPGA, and we need this signal in this pin for clocking FPGA.

This is our configuration:

SIM_SOPT2[FBSL]=11

SIM_SOPT2[CLKOUTSEL]=000 (FlexBus clock, Reset value)

SIM_SCGC7[FLEXBUS]=1

PORTA_PCR6: 0x00000540

PORTA_PCR6[MUX] = 101 (Alt5)

PORTA_PCR6[DSE] = 1 (We tried both configurations, none is working)

Is there anything else I am missing?

We have tried other values for SIM_SOPT2[CLKOUTSEL], but we can't see any kind of clock in that pin.

Ball is correctly soldered because we can move pin as GPIO.

Any suggestions?

Re: CLKOUT in MK70F150 at PTA6

charlesasquith — Thu, 28 Jul 2016 18:23:58 GMT

Hi David,

I understand you didn't mention anything about getting a hard fault, but just for the sake of trying to help you figure out what could be wrong I'll ask - did you enable the clock for Port A?

If you didn't, then you're going to need to set the bit in SIM_SCGC5[PORTA].

I would also recommend executing any code involving the SCGC (Sim Clock Gate Control) register before anything else - to ensure that any peripherals you adjust are clocked before you change them.

Otherwise, I may need more info because to me everything else looks correct, although I could be overseeing something. Maybe you could describe your clock configuration a bit more? What mode is your MCG module in?

Re: CLKOUT in MK70F150 at PTA6

dgalbarra — Fri, 29 Jul 2016 08:16:56 GMT

Hi Charles

Yes, I enabled clock for portA, and no, I'm not getting a HardFault. Actually, the other lines of flexbus are working as expected (FB_ALE, FB_OE...). I can successfully access an external SRAM on different address, because this SRAM doesn't need CLKOUT.

Flexbus is configured in multiplexed mode: 32bit address and 16bit data, left justified.

Clock is configured in FEE mode, using external RTC clock (32.768Hz) and using FLL to get up to almost 48MHz (DMX32=1, DRS=1, this gives a x1464 factor, getting a 47.972352MHz clock)

FlexBus clock is divided by 2, so, I should get a FB_CLKOUT of almost 24MHz

Re: CLKOUT in MK70F150 at PTA6

Robin_Shen — Tue, 02 Aug 2016 02:48:44 GMT

Hi David,

Sorry for late response.

We got confirmation from design team, PTA6 is not assigned any function on ALT5, so it cannot route out CLKOUT on K70. This is a documentation issue and will be fixed later.

Best Regards,

Robin

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