I have been incorporating this device LS7366R into my designs for a few months to count an encoder external of the Prop so that that counter can stay alive for several days on a battery if the power is lost. This avoids rehoming systems on power outages. There is a 12 battery that goes to the LS 7366R board. The board has a 2amp 5v switching reg. The regulator is a solid design I’ve used forever. The Prop drives a BLDC motor driver and reads the counter via SPI to know where the motor is. The part is in use in a lot of designs and is sold by many large automation companies including USDigital which is where i get the encoder. The counter connects via i shielded Cat5 10’ to the encoder located right off the motor shaft.
I have mysteriously had about 4-5 die over the part months on my bench. I attributed one to hot swapping the SPI connection to the Prop. If there were a serious spike I’d think the Prop would die too.
Yesterday I had someone out at site updating software for the Prop and accidentally left some test code in from my bench mock-up. This allow the motor to overshoot and hit s hard stop and stalled out the system with errors. After the error we corrected the code and ran the motor. The counter then had a cumulative error per cycle. There is no possibility of mechanical slip. The encoder is shaft mounted. In testing we spun the motor 4 revs positive and got 7200 approx. Then reverse to the starting point and end up at 70! Repeat the cycle and get 140. 210. 280 etc. accumulating 70 per 4 revs forward and backwards. Needless to say the system will crash after one cycle.
The counter and encoder is only powered from the lithium motorcycle battery(with its smart charger) via 5v SW reg. So any damage would have had to have been EMI or noise from overloading the motor at the initial crash.
I had dismissed the 4-5 dead units as bench oversights but now am having to consider that this device is very delicate. Any thoughts on how this could accumulate an error? The error seems to accumulate only running ++ as the plus value was higher each time than the negative direction.
Photos show the Click counter module with 7366. The black box is the Prop main board and motor driver. Photos are my bench test rig. Not the system that died yesterday.