MCF52259 PSTCLK/TCLK emissions

[carlnormansuret]

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.

[carlnormansuret · Accepted solution]

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There is a newer version of the MCF52259 reference manual, I was using V1 which is missing some information, V4 has more information.