Program not running with external battery

[Xander 0]

Hi,

I've been using the Sony Spresense for a while now, and I am working on a project where the Mainboard should be powered externally. I've read the documentation and in paragraph 1.16 the supplied voltage should be between 3.6v and 4.4v. So I've used a voltage regulator that converts 5v to 4v (Datasheet MCP1702). It can supply 250mA that should be plenty. After connecting the power supply to the Sony Spresense main board the power light does turn on, but it won't run any code. For example turning on LED1 to LED4.

Could some one explain me why this is the case?

Thanks in advance

[CamilaSouza]

Hello, @Xander-0
Can I ask you where (what pin/connector) did you connect the power supply?
Also, can you measure the voltages on pins 3.3V and 1.8V?

[Xander 0]

Can I ask you where (what pin/connector) did you connect the power supply?

I've soldered a 2 pin JST receptacle on the Sony spresense as suggested in the documentation.

After the voltage is regulated to 4V, it is connected with a 2 pin JST receptacle as well. Both ends are connected with the JST plugs that I've cut and soldered together.

Also, can you measure the voltages on pins 3.3V and 1.8V?

The voltage level on both pins are correct after powering up with the external power supply.

[CamilaSouza]

Hello, @Xander-0
Good sign that voltages are good in both pins.
Let's investigate what could've gone wrong.

After flashing some code, could you connect to the board through minicom so we see if it outputs any messages. I want to see if it outputs any error messages through initialization or if it's completely unresponsive.

[Xander 0]

@CamilaSouza said in Program not running with external battery:

After flashing some code, could you connect to the board through minicom so we see if it outputs any messages. I want to see if it outputs any error messages through initialization or if it's completely unresponsive.

Seems fine, but this is the boot when it is plugged in into the computer. And this screenshot is the serial output. But perhaps I am doing something wrong with getting the right readings?

Let me know

[CamilaSouza]

@Xander-0

Hm.. the message from the serial terminal does not tell me much since I don't know what your code is supposed to do, but at least we can see the board is not dead (assuming no message should have appeared from the main core).

Follow up questions:

Does the same thing happen (no code running) when you power through the EXT_VDD pin?

What are you using as power supply before the voltage regulator? Is it a battery? Please give specs
I found this note in the spresense documentation:
"The Spresense can be powered by a USB battery pack. Some USB battery packs require a minimum load current and Spresense may take less than this current, which will cause the USB battery pack to turn off after a few seconds. For reliable USB battery pack operation choose a battery pack that has an 'always on' feature or use a USB 'keep-alive load'."

Can you maybe post a picture of your whole system connected?
(Battery, voltage regulator, spresense board)