Hello All,
Hope you all staying safe and doing well.
Currently I am working on (Raspberry pi 3B+ and IC880a Sheild) LoRa Gateway.
It consist of 1 - Sx1308 & 2 - Sx1257 IC’s & providing Proper Power Supply.
When I checked its CONTINUITY using the Multimeter (without giving Power Supply), the IC880a Sheild shows all the connection are absolutly fine.
But after giving power Supply to the Raspberry pi 3B+ and IC880a Sheild , The CONTINUITY test (using Multimeter) shows like the 3v & 5v & 1.8v supply are short together in REVERSE Direction.
I am confused why this is occured on My Sheild .
Can you please tell me any other solution ?
Any help will be Appreciated.
Thank you.
Your using a multimeter on CONTINUITY test (resistance?) to check a board that is powered up ?
You must never use continuinty test mode to check a live circuit. If you merely get a wrong reading you are lucky; damaging the meter is quite possible, too.
Generally speaking to check power rails in a live system you would use voltmeter mode.
But even that is not without risk - slip with the probe and you may short a power rail to something else, or to ground.
Assuming this isn’t an original design, it’s likely that things are fine as is. If you want to measure, and can separate the expensive radio components from the power supplies, measuring the supply without them could be worthwhile.
Ultimately the biggest concern is that the upstream power source for the whole thing is sufficient. While running, a concentrator card consumes more power than the entire rest of the pi system, so power supplies which are perfectly adequate for a heavily accessorized pi may not be able to reliably run a pi-based gateway. Back when we had pi-like systems with 5v input and linear regulation, we ended up buying 5 amp bricks and putting a large capacitor at the system’s power input and feeding the computer through its GPIO header while the power to the radio went the other way from there and not through the computer. The average might have been around an amp, and the LoRa radio’s consumption doesn’t vary all that much (transmit power is small compared to baseline multichannel receive DSP processing), but the peaks as other loads in the pi part of the system spike could sometimes be an isssue.
no sir, i just checked the CONTINUITY TEST on Board without any power supply.
You’re going to have to be more clear about what this
means then
Then provide detail of what ‘short’ means.
Most would assume your seeing the same resistance as if the test leads were ‘shorted’ together.