Behaviour change when powering with external power source

[chhhhak]

Hi everyone,

I am using a STWINKT1B and I am trying to evaluate its power consumption while operating. The Wifi communication always works well when I power the board by the battery or the USB port but never when I plug it to my voltage source (5V on J5). To be precise, I'm using the STWIN BSP drivers available here  and es_wifi firmware by freertos available here. For the Wifi module to be initialized it requires that it first raise a data ready signal which is on PE11.

Unfortunately when the board is powered though the external source, this signal is never raised and the Wifi connection never occurs. 

Im wondering how changing the power source can change the code behaviour, maybe the code has some unpredictable behaviour, but it's mostly drivers, almost no custom code is executed before it gets stuck.

Thanks for your help.

[SimonePradolini]

Hello @chhhhak 

in your post you are linking a software package for STWIN and another one for a Discovery L4.

Can you please clarify me for which firmware you need support?

Best regards

Simone

[chhhhak]

Hi, sorry for my mistake, I only use the drivers from the STWIN firmware kit.

The function in which the execution gets stuck is 

wait_cmddata_rdy_rising_event

called by

SPI_WIFI_receiveData

from the STWIN_wifi.c file but maybe there is an external actual reason for the WIFI module pin not to have the proper behavior.

[SimonePradolini]

Is your voltage source supplying at least 500mA?

From the hardware point of view the unique difference between USB or external source as supplier is the current capacity of the supplier.

Once checked this, if the issue still persists I can try replicating your setup and debug the software.

Best regards

Simone

[chhhhak]

Thank you for your answer.

As I expect to have a current between 20-80mA I am limiting my power source to 100mA, should the uC be supplied with higher current ? 500mA seems rather high to me.

[SimonePradolini · Accepted solution]

Hello,

500mA was a tentative value, just to highlight that a current limitation can make the device not working properly.

In particular with wifi and during the system boot, where power consumption and energy pick are higher. Surely the module overcomes 100mA.

Have you been able to retest your setup without the current limitation?

[chhhhak]

I have tested to power it with a 300mA limit and it worked well. Indeed I can see its consumption overcoming 100mA especially right after setting up.

Thank for your advice.