Tool/software:
Dear Team,
For my customer's application using as little power as possible is crucial.
They noticed that for one of the unused GPIO pins, namely Port 1 / Pin 4, they currently have it configured as output high:
GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_4);
GPIO_setOutputHighOnPin(GPIO_PORT_P1, GPIO_PIN4);
As they don’t use the pin, they planned to change it to output low. However, before doing so they wanted to perform current measurements and check our recommendations.
TI recommends in the datasheet:
Unused pins to be configured as outputs.
1.) We are wondering, does TI also have a recommendation for output level (low or high) for unused pins?
They did some quick measurements ourselves which yielded:
|
Configuration |
Current consumption |
Increase in current consumption |
|
Output high |
11.54 uA |
|
|
Input with pulldown |
11.57 uA |
+0.03 uA |
|
Input with pullup |
11.55 uA |
+0.01 uA |
|
Input without pullup/down |
11.55 uA |
+0.01 uA |
|
Output low |
11.60 uA |
+0.06 uA |
It looks like the plan of changing the unused pin from output high to output low is not ideal with regards to power consumption.
2.) Did TI perform power consumption measurements for different GPIO configurations as well?
They performed the current measurement using Joulescope JS110. The P1.4 pin is unconnected. They compared the different current consumptions for the application with the MSP430FR6047 by only changing the configuration of the P1.4 pin as shown in the table.
Best regards,
Daniel Waleniak
