JM128 Pins not operating correctly

[ariclowe]

Hello everyone,

Id appreciate any advice I can on a little problem Im experiencing with the JM128 chip.  Im currently interfacing to an external SRAM chip with the JM128.  The problem that Im having is when I set the address on the pins ( Most sig. byte port D, Mid sig. Port E, and least sig. byte Port F).  I need to use 3 ports to address 500K spaces.  The problem however is within Port E pins 0 and 1.  The rest of the pins are set correctly however Port E pin 0 is ALWAYS high, and Port E pin 1 sits at about 1.5 V regardless of what I set them at.  Obvisouly this posses a significant problem in addressing a specific memory address when two of the middle bits are consistently erraneous.  Im not using any of these pins for any other function of that this and have not enabled any serial communication that these two pins could potentially be used for.  Any thoughts out there from the great Freescale Masters??

Thanks,

Aric

[ariclowe]

OK I found it...you were right...had some old code still stuck in there from the USB stack that was using the UART for talking to the terminal window I suppose...thanks again Rich

[ariclowe]

Yeah I tried that already.  Removed the jumpers, and set SCI1C1_SPE to zero.

[RichTestardi]

Do you have uart (SPI) 1 configured somehow?  uart 1 shares those pins for its transmit and receive data.  Check register SPI1C1 and make sure bit 6 (SPE) is a 0 (meaning the uart is not stealing pins pte0 and pte1), and then check your board to make sure you are not expecting a uart to be there -- on the demo boards you can typically remove a couple of jumpers to leave those pins alone.

-- Rich