Weird behaviour of VR3.1 module in circuit - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: June 29, 2024, 10:23:23 pm
content: Hi there.I am starting debugging a circuit of mine, from last year. It features an Attiny804 controlling a couple of led strips and itself controlled either by buttons or avoice recognitionmodule.Basically a switch (J7) turns on or off a mosfet which, in turn, connects the "GND" line of the recognition module. The switch status is sensed by the tiny which executes code to enable the mic or the buttons.Everything works fine and dandy as long as my PSU is powering the circuit. But the friend I built this for uses powerbanks to power it and, while buttons work fine, it turns out that the VR module does not.Furthermore I tried to see the changes in current by using my dmm6500 to capture whether this could be a problem BUT with the multimeter in-circuit, while it clicked through the ranges, the VR module started working even powered from the PB.To measure current I then tried and put a 1R resistor (with breakout cables and a breadboard) and connected my dmm in parallel to measure voltages (I thought the DMM was messing something up) and 1R was enough in series to make it work fine, it seemed. I tried then, experimenting, with a 0R1 and it stopped working again. I was able to measure (I don't remember in which way) around 180mA of peak startup current.I then put everything back as it was (ie: no resistances, PB not working, PSU working), but I had been clumsy and accidentally disconnected the VCC cable from the VR module and… even with the powerbank everything was working!! I assume power trickled down from the TX-RX lines, but I don't get how or why I have this behaviour. I really want to learn something here.Can you please give me any pointers? At this point I'm scared of VR modules.CheersPS: I attached the schematic, sorry if it's partly Italian, everything should be there tho

author: m k
author_rank: Super Contributor
timestamp: July 07, 2024, 12:14:50 pm
content: Is the Command part drawing as it should?

author: Moriambar
author_rank: Unknown
timestamp: July 07, 2024, 01:16:36 pm
content: Quote from: m k on July 07, 2024, 12:14:50 pmHi, thanks for your reply.I don't get your question, though...

author: m k
author_rank: Super Contributor
timestamp: July 07, 2024, 06:24:59 pm
content: Is that part of the pdf as the real thing is actually connected?

author: Moriambar
author_rank: Unknown
timestamp: July 10, 2024, 03:29:07 pm
content: Quote from: m k on July 07, 2024, 06:24:59 pmYes, I'm sorry, perhaps it's drawn poorly. J7 is across C5 (which is there for debouncing) and it's connected to a switch (external).

author: m k
author_rank: Super Contributor
timestamp: July 10, 2024, 06:56:50 pm
content: I saw different and wrong net examples around these voice modules.So check that yours is correct.Check also power bank voltage of non working situation.

author: Moriambar
author_rank: Unknown
timestamp: July 14, 2024, 12:42:25 pm
content: Quote from: m k on July 10, 2024, 06:56:50 pmI think mine is correct. The purpose is to "sense" whether the module is active or not, thus doing different things in the mcu.The problem is that with the PSU everything works fine every tiime.I'll try and check the voltage from the bank whenever I get the chance (I have the circuit no longer), but why cutting the power line, hence getting power from the serial interface does work?I suspect that's something to do with my cap, maybe?

author: m k
author_rank: Super Contributor
timestamp: July 15, 2024, 04:27:35 pm
content: Something is clearly overloaded.Powering from data line situation doesn't change to worse if you add extra power.How is the VR connected exactly?No pin names only, tell physical locations compared to other pins.