MOD54415 PA0 and PA1
Posted: Fri Mar 08, 2019 7:40 am
I'm migrating an existing project from the MOD5272 to the MOD54415.
Initially I hacked on of our existing PCBs to reroute the pins that I needed into the correct locations. I did this for about 95% of the pins and then had a little test PCB made up that we could plug in.
for the last 2 pins, I arbitrarily picked PA0 and PA1 to drive a CMOS based mux to select different analog input sources.
Years ago, someone had ordered a MOD54415 rev 1.5 board, which I was using, and I could not trigger PA0/PA1. With a little searching on the forum I found a post suggesting the documentation was lacking here and suggested PA0/PA1 may not work as expected prior to rev ~1.8
I ordered a new board, Rev 1.10, and I now have control over PA0 and PA1.
First thing I noticed with this is that when I configure them to be GPIO pins, it breaks AutoUpdate.
No biggie, as the work around simply involved returning the pins to their reset state:
So no biggie here.
I thought perhaps the slew rate was the issue, hence the configuration, but it doesn't appear to make an obvious difference.
However, very occasionally I'll see 'spikes' in my recorded data. By very rare, it was 3 over the course of 12 hours last night, and I get a sample every 10 seconds, so roughly 0.1% of my data is bad. In the lab, it's obvious, in the field is another story. To me, it appears as though the spikes in my data are caused by the MUX not switching when PA0 and PA1 are supposed to be toggled. These are toggled every 250ms. 0x00, 0x01, 0x10, repeat.
I don't see these spikes on the MOD5272 (there I'm using PA0 and PB7 due to this being added later on in the life cycle of the hardware) on the same PCB setup (I've simply removed my break out board to compare)
I think my next step would be likely to try it on two other pins, but before I go hacking my test PCB, I was wondering if anyone has any insight?
Cheers,
Keith
Initially I hacked on of our existing PCBs to reroute the pins that I needed into the correct locations. I did this for about 95% of the pins and then had a little test PCB made up that we could plug in.
for the last 2 pins, I arbitrarily picked PA0 and PA1 to drive a CMOS based mux to select different analog input sources.
Years ago, someone had ordered a MOD54415 rev 1.5 board, which I was using, and I could not trigger PA0/PA1. With a little searching on the forum I found a post suggesting the documentation was lacking here and suggested PA0/PA1 may not work as expected prior to rev ~1.8
I ordered a new board, Rev 1.10, and I now have control over PA0 and PA1.
First thing I noticed with this is that when I configure them to be GPIO pins, it breaks AutoUpdate.
No biggie, as the work around simply involved returning the pins to their reset state:
Code: Select all
void InitializeHardware()
{
//Reference input PA0,1
J1[9].function(PINJ1_9_GPIO); // PA0 - GPIO -- LBS
J1[10].function(PINJ1_10_GPIO); // PA1 - GPIO -- ABS
// PA0,1 are BE1,0 which are fsr pins. lowest slew rate has a rise time of 16ns, and fall time of 21ns
sim1.gpio.srcr_fb1 = (sim1.gpio.srcr_fb1 & ~0x03) | 0x00; // 'lowest' (0x00) slew rate.
J1[9].drive(); // PA0 - output
J1[10].drive(); // PA1 - output
J1[9] = 0;
J1[10] = 0;
}
void ShutdownHardware()
{
J1[9].function(PINJ1_9_FB_BE1); // PA0, PA1 as GPIO will cause the update programs to fail and corrupt the firmware.
J1[10].function(PINJ1_10_FB_BE0);
sim1.gpio.srcr_fb1 |= 0x03; // 'highest' (0x03) slew rate.
J1[9].read();
J1[10].read();
}I thought perhaps the slew rate was the issue, hence the configuration, but it doesn't appear to make an obvious difference.
However, very occasionally I'll see 'spikes' in my recorded data. By very rare, it was 3 over the course of 12 hours last night, and I get a sample every 10 seconds, so roughly 0.1% of my data is bad. In the lab, it's obvious, in the field is another story. To me, it appears as though the spikes in my data are caused by the MUX not switching when PA0 and PA1 are supposed to be toggled. These are toggled every 250ms. 0x00, 0x01, 0x10, repeat.
I don't see these spikes on the MOD5272 (there I'm using PA0 and PB7 due to this being added later on in the life cycle of the hardware) on the same PCB setup (I've simply removed my break out board to compare)
I think my next step would be likely to try it on two other pins, but before I go hacking my test PCB, I was wondering if anyone has any insight?
Cheers,
Keith