This is a follow up from this discussion here https://vellenich.ch/index.php/table-content/data-sniffer-box
If you don't have enough PC COM ports, you can replace one with a bluetooth module. I am using an HC-05 you can find easily and they are cheap enough.
They need 5 VDC supply but their logical levels are from 0–3.3 VDC. It's important to know that because their inputs are not 5 volts tolerant, at least I did not find any info about this topic. So we assume they are not tolerant to 5 VDC!
We need as well a couple of RS232 to TTL level converters (available in quantity and cheap). These 2 modules are powered at 3.3 VDC. It's again important so that their data (RXD/TXD) voltages match with the HC‑05 module input/output levels.
The DUT device you are going to connect to should have 0–3.3 VDC levels.
Note 1: Don't forget to wire the ground between your DUT and your power supply :-)
Note 2: I powered the HC‑05 with 3.3 VDC and it worked. This was to program it with a Teensy board . For this current project, better stick to 5 VDC.
Note 3: DC/DC converters: they are everywhere, just google it!
Schematics (with the sniffer box schema):
Everything in a box with the converter
Together with the data sniffer box: It matches perfectly :-)
