NRF52 BLE UART + Proximity

[Sunil vignesh]

Hi,

I am using NRF52832 to read the sensor data (BMI160 accelerometer sensor) by using I2C.

I try to send the sensor data to mobile by using BLE_UART. upto this i finished now. I need is.

1.calculate the BATTERY level without using ADC. is there any register used to read the battery?

2. need to know the paired device distance. or proximity?

[bjorn-spockeli]

HI Sunil, 

Q1: There are no internal peripheral that measures VDD on the NRF52. You need to use the ADC to measure VDD. Alternatively, if yo ujust want to know if VDD has fallen below a certain threshold, then you can use the LPCOMP. 

Q2: You can use the RSSI to determine of the connected device is close of far away, see S132 SoftDevice v6.1.0: RSSI get sample.

Best regards

Bjørn 

[Sunil vignesh]

Hi Bjorn,

I need a clarification in BLE_Proximity. in that I download the code and I connect  with Mobile phone. It ask for pair the device. and pair the device.

In app it shows the Battery level and location enable disable option.

1) battery level is measure based on LPCOMP or using ADC pin connection?

2) the proximity output as led 2 ON is this because of RSSI ?

can you please give a brief explanation about this BLE_Proximity.

If the battery level measure due to ADC means shall i get the schematic of the NRF52832 development board. I need a bit clarification about this.

[Sunil vignesh]

i got one more problem that is while pair with device. after some time i did un-pair in mobile phone. and i reconnect with the device but it doesn't pair with phone

in log it shows

<info> app: No Alert.
<info> app: Connected.
<info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x0, procedure: Bonding, error: 133
<info> app: Fast advertising.
<info> app: Disconnected.
<info> app: No Alert.
<info> app: Connected.
<info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x0, procedure: Bonding, error: 133
<info> app: Fast advertising.
<info> app: Disconnected.

[bjorn-spockeli]

See step 24 in Proximity Application

Press and hold Button 2 (erase bonds) for 5 seconds and connect with the first nRF Connect. Observe that the link encryption is OFF ("Security updated, mode:1, level:1") and that no notifications are received.

[bjorn-spockeli]

Q1: It uses the ADC, see Proximity Application. 

Q2: See the Testing section of Proximity Application for the description of LED indications. 

The nRF52 DK Hardware schematics and layout can be found here.

[Sunil vignesh]

is voltage divider used in any pin connection..?

what does the pin DCC,DEC1,DEC2,DEC3,DEC4 can you explain please.

is there any hardware Voltage divider or any other to do ADC process?

or by internal VDD -  SAADC will calculate the battery level..

Actually I need a simple solution sir. I need to calculate the battery level like (0% - 100%) i need to calculate each and every single percentage.

please give a line diagram to connect any external pin connection to read the battery level.

or is there any functions to clearly read the battery level without any external analog pins...?

[bjorn-spockeli]

Q1: DCC,DEC1-4 are decoupling pins for the various internal modules

Q2: If the battery voltage is above the maximum VDD of the nRF52, (i.e 3.6V) and stepped down to 3.6 or below, then you need to use an external voltage divider. If it is within the 1.7v- 3.6v, then you can connect VDD to the SAADC internally. 

See https://devzone.nordicsemi.com/b/blog/posts/measuring-lithium-battery-voltage-with-nrf52 and https://devzone.nordicsemi.com/f/nordic-q-a/17183/adc-input-voltage---nrf52/66004#66004

[Sunil vignesh]

Hi bjorn,

i got the SAADC values by connecting the P0.02 pin to VDD. if the voltage drop occur this adc value becomes drop. is this correct one or any thing to be change.

if the method that i done is correct. for hardware protection we need add any resistance or any internal protection circuit is there for the pin.?

[bjorn-spockeli]

The SAADC of the nRF52 can measure VDD by setting NRF_SAADC_INPUT_VDD as the input. This is an internal connection so you do not have to use one of the GPIOs You can find examples for the nRF52 here. 

This eliminates the need for any external protection circuits. 

[Sunil vignesh]

thank you  i got the saadc value. i need to interlink with my code.

is there any simple solution to find the distance between the mobile phone and the DK board

is there any simple function to read the RSSI pin of bluetooth connection. so that i alert the person if the device is in out of range

is it possible to merge both BLE_proximity and BLE_Beacon . because i need to know the distance, range in dBm and out of range need to alert the person. simultaneously it needs to read the sensor data and through it in BLE_UART.

AIM is : NRF + TWI + BLE_UART + proximity + distance + saadc