Author Topic: Unexplained power draw floating UART Simblee  (Read 211 times)

blieber

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Unexplained power draw floating UART Simblee
« on: March 22, 2017, 01:04:55 PM »
Trying to debug a custom board with Simblee, noticed strange symptoms where:
1. When UART is attached to 5V rails get expected ULP current draw of <10uA
2. When remove UART pins from rails to floating ULP current draw jumps up to ~120uA
3. If I've done analog write on any pin since setup this, ULP current draw is ~1mA

My board is actually running 3.3V -- my guess is somehow when UART pins pulled to 5V this disables some of hardware features in ULP (although these features seem to work normally otherwise... hmmm this maybe isn't the best theory).

Also tried:
-- Pulling pins to 0V or 3.3V
-- Serial.end()
-- Setting UART pins to explicit inputs/outputs
-- NRF_UART0->ENABLE = (UART_ENABLE_ENABLE_Disabled << UART_ENABLE_ENABLE_Pos)
None of these seemed to reduce/remove increased current draw when UART pins are removed from rails

tolson

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Re: Unexplained power draw floating UART Simblee
« Reply #1 on: March 22, 2017, 08:07:47 PM »
Don't know what is happening, other than NO pin should be pulled to 5V. The max is 3.6V. Perhaps you stressed it.

 

anything