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I've built a circuit board for a project around the TMX320F28235 and just assembled my first board. However, I'm having a hard time getting it to power-up correctly. It seems that all the pull-ups on the GPIO pins have a hard time pulling-up, even with no load attached including namely hte RST and JTAG programming pins. I see readings of 2.0V - 2.8V and don't understand why they should ever be less then 3.2V or so with no load? I've verified my power supplies (3.29V with 20mV ripple, and 1.88V with 10mV ripple). The oscillator for the chip powers up and oscillates at 30MHz no problem as well. Additionally, the chip isn't drawing any excessive current (approx 50mA total).
Anybody have any ideas? It seems that whatever internal nets on the chip power the pull-ups are some how shorting to ground. And it isn't just a few pins on the chip, I checked GPIOs on all 4 sides with similar results. Additionally, all the VDDIO and VDDCORE pins and decoupling caps are reading a strong 3.3V.
I have another chip on the board that operates independent of the DSP and it functions just fine.
Thanks in advance,
- Kyle
