topic Re: MCF52259 PSTCLK/TCLK emissions in ColdFire/68K Microcontrollers and Processors

MCF52259 PSTCLK/TCLK emissions

carlnormansuret — Mon, 26 Sep 2016 03:41:27 GMT

Hi All,

I have been doing some emissions testing and PSTCLK/TCLK pin is causing us to fail (80Mhz fundamental).

I have JTAG_EN low (we dont use JTAG). This trace between pin 43 (LQFP) and the debug header is just acting as an antenna and radiating 80Mhz.

I dont want this pin oscillating unless the debugger is attached, how do I stop this pin unless the debugger / programmer is attached? Or, what is the ideal way to stop it radiating so much noise.

Re: MCF52259 PSTCLK/TCLK emissions

carlnormansuret — Tue, 27 Sep 2016 03:24:34 GMT

Hi Guys,

After some searching I found a way to shut down a lot of the noise generated by the MCF52259!

Shut down the PST[3:0] pins, i set them to outputs and set them low

PDDPAR &= (~0b00001111);
DDRDD |= 0b00001111;
PORTDD &= (~0b00001111);

turn off the PSTCLK pin so it does nothing

SYNCR |= 0x0040;

There is a newer version of the MCF52259 reference manual, I was using V1 which is missing some information, V4 has more information.