Hi all,
I have created my own Teensy 3.1 PCB, but it does not respond as expected (i.e. no USB-Serial-Connection entered in the Teensyduino IDE). Connecting a standard Teensy 3.1 works.
I have read the other threads. I did not connect VOUT33 initially as I am using an external Power Supply circuit (Lipo charger and Voltage regulator). After reading a few posts here I soldered a cable from VOUT33 to 3V3. The other posts aren't clear about wether I should connect VREGIN to VCC too. I tried both ways (i.e. letting VREGIN floating and currently it is connected to 3V3). 3V3 is the output from my voltage regulator.

I have a bit of noise on the 3V3 line, but I am not quite sure if this is heavy noise or if it's ok. I have attached an image showing it.
As described in other threads at started RESET and PROG-Lines of the Minitan54 are supposed to be high, I noticed that RESET is low, goes high every 50us and then goes low again. Paul already described this to be correct. Pressing the PROG-Button (pulling it LOW) does pull RESET to low too, so that is correct too I think.
In this image you can see the RESET-Line going low while pressing the button, then there are a few LOW pieces, followed by the LOW-HIGH-LOW pulses every 50us. I have also attached a detailed shot of these Pulses:


When RESET is low the Minitan54 will program the MK20, so there will be data transfer. This is what I read in another thread. And this is what I get. I am not quite sure if the pin assignment in the images is correct, but these are the signals from PTA0 and PTA3. They look like clock and data. Are they too noisy?
This is PTA3:


And PTA0:


(as said before it could be the other way round, but I doubled checked that my connections are the same as in the Teensy Schematic).
Next the MK20 should bring up the crystal. But it doesn't. I am using a 8pF 16 MHZ crystal, I have a ground plane. And the tracks are as short as possible (so very, very close).
I don't really know what to do next. Could it be the crystal? Or is there another problem? Anything I can check?
Thanks very much for your help.
Phillip
I have created my own Teensy 3.1 PCB, but it does not respond as expected (i.e. no USB-Serial-Connection entered in the Teensyduino IDE). Connecting a standard Teensy 3.1 works.
I have read the other threads. I did not connect VOUT33 initially as I am using an external Power Supply circuit (Lipo charger and Voltage regulator). After reading a few posts here I soldered a cable from VOUT33 to 3V3. The other posts aren't clear about wether I should connect VREGIN to VCC too. I tried both ways (i.e. letting VREGIN floating and currently it is connected to 3V3). 3V3 is the output from my voltage regulator.

I have a bit of noise on the 3V3 line, but I am not quite sure if this is heavy noise or if it's ok. I have attached an image showing it.
As described in other threads at started RESET and PROG-Lines of the Minitan54 are supposed to be high, I noticed that RESET is low, goes high every 50us and then goes low again. Paul already described this to be correct. Pressing the PROG-Button (pulling it LOW) does pull RESET to low too, so that is correct too I think.
In this image you can see the RESET-Line going low while pressing the button, then there are a few LOW pieces, followed by the LOW-HIGH-LOW pulses every 50us. I have also attached a detailed shot of these Pulses:


When RESET is low the Minitan54 will program the MK20, so there will be data transfer. This is what I read in another thread. And this is what I get. I am not quite sure if the pin assignment in the images is correct, but these are the signals from PTA0 and PTA3. They look like clock and data. Are they too noisy?
This is PTA3:


And PTA0:


(as said before it could be the other way round, but I doubled checked that my connections are the same as in the Teensy Schematic).
Next the MK20 should bring up the crystal. But it doesn't. I am using a 8pF 16 MHZ crystal, I have a ground plane. And the tracks are as short as possible (so very, very close).
I don't really know what to do next. Could it be the crystal? Or is there another problem? Anything I can check?
Thanks very much for your help.
Phillip