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Altera_Forum's avatar
Altera_Forum
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9 years ago

custom i2c

Just after a quick/general comment as I am a bit new to HDL. I was struggling to get much over 30kHz on my i2c connection because my code on my Nios II processor was not handling the interrupts...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

Hi Steffen,

I'm using "weak pull up resistors"...

set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to D5M_SCLK

set_instance_assignment -name WEAK_PULL_UP_RESISTOR ON -to D5M_SDATA

On the slave side there is a 1.5K pull up resistor on the data line.

I'm not sure if it makes much difference (being open drain?), but in the pin planner, the drive current is set to 16mA. (I use values 0 and 'z')

Slew rate is the default 1.

The little shark fin is just the remains of ack driven by the slave (meant to be low).

I don't think there are any capacitors in the circuit as such. However there might be some protection resistors in line.