Before the test of EasyTK1_IO on Jetson TK1 I prefered to do a instrumental test of Jetson TK1 voltage level adapter ( EasyTK1_IO ) to analize & solve potentially-destructive problem.
To do the test I’ve used this test equipment:
- AFG3022B Tektronix Dual Channel Arbitrary Function Generator
- RIGOL DS1074Z 4 Channel 70Mhz Oscilloscope
Part of EasyTK1_IO scheme under test
this is the parto of EasyTK1_IO, Jetson TK1 voltage level shifter, scheme under test. On left side you can see LowVoltage side signal, this is Jetson TK1 side. On right you can see the “HighVoltage” signal side, this is device side. V_PUo-3 lave is power supply input from external device and can be 1,8V to 5V
Test Setup of EasyTK1_IO voltage level shifter
I’ve soldered on EasyTK1_IO minimum required components only, voltage-level component of some channel essentially.
I’ve connected 2 channel of my oscilloscope and output of signal generator as figure:
EasyTK1_IO measure report
In this image I’ve tested HighVoltage to LowVoltage trasmission without power supply. Output signal is below 1,8V acceptable on Jetson TK1:
In this table I’ve summarized some test with different frequency and voltage:
|Report 1||Report 2||Report 3|
|150Khz|| from 3,3|
|150Khz|| from 1,8|
Conclusion about EasyTK1_IO
Jetson TK1 is safe but 10K ohm pullup resistor can be a limit in High frequency operation. I can reduce this pull-up resistor but in different devices, like I2C device, there are pull-up resistor, they will reduce effective pull-up increasing frequency performance.