High current issue resulted from UART in nRF52832

RE: High current issue resulted from UART in nRF52832

conrad — Mon, 11 Jun 2018 05:18:38 GMT

Hi hmolesworth,

Thanks for your reply. I check the connection of my board. The power of nRF52832 is form USB to TTL 3.3v output pin.

With the same connection, if I don`t initialize the UART in my code, the current is normal. So it seem not only related to hardware connection.

RE: High current issue resulted from UART in nRF52832

conrad — Mon, 11 Jun 2018 03:58:56 GMT

Hi Kristin,

This morning I do several tests based on the "ble_app_uart" code. I add a 10ms APP_TIMER to be the same with my

appliction code. The following are the test conditions and results:

Items / Conditions / Results

1/ Uart not initialized / current is normal (46uA)

2/ Uart initialized / current is kept high (2.26mA)

3/ Uart initialized; UART disabled by app_uart_close() after ble_stack_init() / After power on, the current is kept high (2.26mA) for several seconds.

4/ Uart initialized; UART disabled by app_uart_close() before ble_stack_init() / The current is normal as test item 1.

All the above test conditions are Rx and Tx pins disconnected. The nRF52832 is powered by USB_TO_TTL dongle 3.3V.

The main loop of my code:

int main(void)
{
uint32_t err_code;
bool erase_bonds;

uint32_t i;

// Initialize.
APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
uart_init();

//buttons_leds_init(&erase_bonds);
ble_stack_init();

gap_params_init();
services_init();
advertising_init();
conn_params_init();

app_timer_create(&fbm320_timer_id,
APP_TIMER_MODE_REPEATED,
timer_fbm320_handler);
app_timer_start(fbm320_timer_id, APP_TIMER_TICKS(10, APP_TIMER_PRESCALER), NULL);

// printf("\r\nUART Start!\r\n");

err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
APP_ERROR_CHECK(err_code);

app_uart_close();

// Enter main loop.
for (;;)
{
power_manage();
}
}

RE: High current issue resulted from UART in nRF52832

hmolesworth — Fri, 08 Jun 2018 21:46:14 GMT

The USB to TTL dongle will provide power to the nRF52832 via the internal schottky protection clamp diodes unless the USB to TTL voltage (typically 3.3 volts) is the same as the nRF52832 Vdd (typically 2.8 volts or less). With the Rx and Tx line disconnected you are seeing the true consumption, with Rx and Tx connected the measured value is incorrect. As a test, use the USB to TTL dongle voltage as the Vdd source for the nRF52832; usually this is available on a header unless it is the encased type. When connected thus the Rx and Tx will work but you will see the higher current consumption.

This is commonly referred to as phantom power.

RE: High current issue resulted from UART in nRF52832

conrad — Fri, 08 Jun 2018 14:55:04 GMT

Hi Kristin,

I had not check the result if I use the uart example in the peripheral folder. I will test the example to see if it is the same in

next Monday. Thanks for your suggestion.

RE: High current issue resulted from UART in nRF52832

FormerMember — Fri, 08 Jun 2018 12:19:53 GMT

Do you see the same if you test the uart example in the peripheral folder ( ..\examples\peripheral )?