low power wearable electronics.

RE: low power wearable electronics.

JONATHAN LL — Thu, 03 Aug 2023 08:55:07 GMT

The second layer:

- The section under the RF path, so that is the area from where the nRF52 SoC is and all the way until the antenna. It should either have a solid copper plane, not traces or paths that separate copper sections under that area.
- Section under the Antenna needs to have a cut out(no copper under the antenna area)

There is some info here in this video from Altium that does show what to do around the antenna. https://youtu.be/2U1ngG5R5Pw?t=659

Regards,
Jonathan

RE: low power wearable electronics.

LoPow@ — Mon, 31 Jul 2023 09:16:13 GMT

Please ,can you tell me what actually needs to be done in the second layer?

RE: low power wearable electronics.

JONATHAN LL — Fri, 28 Jul 2023 19:24:25 GMT

Hi,

Pardon the slow response.

The layout is still not ideal, all the light blue area marked in the drawing under needs to be removed, no GND plane in that section.
All the dark Blue area should be connected to GND plane on top layer. The Dark circle you need to add a matching network. Ideally a pi network but a single shunt is minimum.

Second layer, the light blue are needs to be a single continues GND plane.

[quote user="dhananjay1"]Can you tell me what is the actual value of R1 resistor?[/quote]

Its optional and specs can be seen here:

The value should be 2.2 Ohm.

Regards,
Jonathan

RE: low power wearable electronics.

LoPow@ — Wed, 26 Jul 2023 06:02:41 GMT

In your reference schematic,there will be a resistor R1 which is connected to the VBus.and value of R1 will be 2R2 as per your schematic.....Can you tell me what is the actual value of R1 resistor?

RE: low power wearable electronics.

LoPow@ — Sat, 15 Jul 2023 07:16:52 GMT

Please reffer the attached documents........As per your suggestions,I have made changes.....Please check it and suggest corrections.....

devzone.nordicsemi.com/.../_5F00_autosave_2D00_tanvi_5F00_updated_2D00_-reference.pdf devzone.nordicsemi.com/.../Low-power-final.csv

RE: low power wearable electronics.

JONATHAN LL — Tue, 11 Jul 2023 07:41:38 GMT

Hi LoPow@ , did you mix up what ticket you replied to? Was this where you intended to update https://devzone.nordicsemi.com/support/310814 ?

[quote user="dhananjay1"]Is there any reason for this, that all critical components should be close to the chip....?[/quote]

Yes, it is important to follow the layout recommendations. Deviation from can cause unexpected issues. Like reduced RF performance and it could also effect the devices stability making it more prone to be effected by external EMI.

Regards,
Jonathan

RE: low power wearable electronics.

LoPow@ — Thu, 06 Jul 2023 03:54:59 GMT

Is there any reason for this, that all critical components should be close to the chip....?

RE: low power wearable electronics.

LoPow@ — Wed, 05 Jul 2023 08:29:08 GMT

How to use TWIM for reading and writing data from an external sensor with nrf5340dk.

Boss

My target is to read and write data from a sensor using bare metal programming for the nrf5340dk with minimum power consumption.

I had a problem with this program. Though the program does not give any error, it seems to be unable to read data from the sensor.

Our program code is given below:

#include "nrf.h"

//SCL & SDA LINES
#define PIN_SCL           3
#define PIN_SDA           4
#define PORT_NO           1

#define SLAVE_ADDRESS     0xDF

// Definitions for delay function
#define SYSTICK_LOAD_VALUE 64000 // for each ms
#define CTRL_ENABLE (1U << 0)
#define CLK_SOURCE (1U << 2)
#define CTRL_COUNTFLAG (1U << 16)
// Delay function
void delay(int delay) {
    // Load the number of clock cycles per millisecond
    SysTick->LOAD = SYSTICK_LOAD_VALUE;
    // Clear SysTick current value register
    SysTick->VAL = 0;
    // Enable SysTick and select processor clock source
    SysTick->CTRL = CTRL_ENABLE | CLK_SOURCE;

    for (int i = 0; i < delay; i++) {
        // Wait until the count flag is set
        while ((SysTick->CTRL & CTRL_COUNTFLAG) == 0) {}
    }
    SysTick->CTRL = 0;
}

void gpioEnable(void){
NRF_P1_S -> PIN_CNF[PIN_SCL] = (GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos) |
                                  (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
                                  (GPIO_PIN_CNF_MCUSEL_Peripheral << GPIO_PIN_CNF_MCUSEL_Pos);
NRF_P1_S -> PIN_CNF[PIN_SDA] = (GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos) |
                                  (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
                                  (GPIO_PIN_CNF_MCUSEL_Peripheral << GPIO_PIN_CNF_MCUSEL_Pos);
}

void i2cEnable(void){
NRF_SPIM1_S -> ENABLE = (SPIM_ENABLE_ENABLE_Disabled << SPIM_ENABLE_ENABLE_Pos);
NRF_SPIS1_S -> ENABLE = (SPIS_ENABLE_ENABLE_Disabled << SPIS_ENABLE_ENABLE_Pos);
NRF_TWIS1_S -> TASKS_STOP = (TWIS_ENABLE_ENABLE_Disabled << TWIS_ENABLE_ENABLE_Pos);
NRF_UARTE1_S -> ENABLE = (UARTE_ENABLE_ENABLE_Disabled << UARTE_ENABLE_ENABLE_Pos);
NRF_TWIM1_S -> ENABLE = (TWIM_ENABLE_ENABLE_Enabled << TWIM_ENABLE_ENABLE_Pos);
}

void i2cDisabled(void){
NRF_TWIM1_S -> ENABLE = (TWIM_ENABLE_ENABLE_Disabled << TWIM_ENABLE_ENABLE_Pos);
}
void i2cConfig(){
//The SCL and SDA signals are mapped to physical pins using the PSEL.SCL and PSEL.SDA registers.
//PSEL.SCL and PSEL.SDA must only be configured when the TWI master is disabled.
NRF_TWIM1_S -> PSEL.SCL = (PIN_SCL << TWIM_PSEL_SCL_PIN_Pos) |
                            (PORT_NO << TWIM_PSEL_SCL_PORT_Pos) |
                            (TWIM_PSEL_SCL_CONNECT_Connected << TWIM_PSEL_SCL_CONNECT_Pos) ;

NRF_TWIM1_S -> PSEL.SDA = (PIN_SDA << TWIM_PSEL_SDA_PIN_Pos) |
                            (PORT_NO << TWIM_PSEL_SDA_PORT_Pos) |
                            (TWIM_PSEL_SDA_CONNECT_Connected << TWIM_PSEL_SDA_CONNECT_Pos);
NRF_TWIM1_S -> FREQUENCY = (TWIM_FREQUENCY_FREQUENCY_K100 << TWIM_FREQUENCY_FREQUENCY_Pos);
}

int i2cRead(uint8_t slave_addr, uint8_t mem_addr, uint8_t *data){
//volatile int tmp;
NRF_TWIM1_S -> TASKS_STARTRX = (TWIM_TASKS_STARTRX_TASKS_STARTRX_Trigger << TWIM_TASKS_STARTRX_TASKS_STARTRX_Pos);
while (!(NRF_TWIM1_S -> EVENTS_RXSTARTED & 1)){};
NRF_TWIM1_S -> ADDRESS = (slave_addr << TWIM_ADDRESS_ADDRESS_Pos);
while (!(NRF_TWIM1_S -> ERRORSRC & 2)) {};
NRF_TWIM1_S -> ADDRESS = (mem_addr << TWIM_ADDRESS_ADDRESS_Pos);
while (!(NRF_TWIM1_S -> EVENTS_RXSTARTED & 1)){};
NRF_TWIM1_S -> RXD.PTR = (uint32_t)&data;
NRF_TWIM1_S -> RXD.MAXCNT = sizeof(data);
NRF_TWIM1_S -> TASKS_STARTRX = (TWIM_TASKS_STARTRX_TASKS_STARTRX_Trigger << TWIM_TASKS_STARTRX_TASKS_STARTRX_Pos);
while(!(NRF_TWIM1_S -> EVENTS_LASTRX & 1)){};
NRF_TWIM1_S -> TASKS_STOP = (TWIM_TASKS_STOP_TASKS_STOP_Trigger << TWIM_TASKS_STOP_TASKS_STOP_Pos);
NRF_TWIM1_S -> EVENTS_LASTRX = 0;
return (int) (*data);
}

int main(){
int a;
i2cDisabled();
gpioEnable();
i2cConfig();
i2cEnable();

while (1){
    a = i2cRead(SLAVE_ADDRESS, 0,(uint8_t*) &a );
    printf("The data read is : %d", a);
    delay(1000);

}
return 0;
}

RE: low power wearable electronics.

JONATHAN LL — Tue, 04 Jul 2023 15:23:55 GMT

Hi,

There needs to be a cutout area for the antenna.

Move the critical component closer to the nrf52 SoC. Use our ref design as a guide here and try to copy exactly. Here is a showcase https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html?cp=5_0_0_6_2_15#layout

See the response I have here : https://devzone.nordicsemi.com/f/nordic-q-a/98199/matching-network-placement-and-routing-ble-antenna-routing It includes some links to some guides that have more info.

Regards,
Jonathan

RE: low power wearable electronics.

LoPow@ — Mon, 03 Jul 2023 11:31:50 GMT

This is the updated version of Low Power Wearable Electronics.Please check it and suggest corrections....

RE: low power wearable electronics.

JONATHAN LL — Mon, 22 May 2023 07:21:30 GMT

Hi LoPow@ ,
The cost saving is not worth it in this case. The performance will be terrible and not representative of a two(multi) layered design so it will not be representable of the final product.

So this is not recommended. Pleas follow the reference layout to achieve good results. Failing to follow the design guidelines can result in a non working device.

The center pad of the SoC needs to be connected to the rest of the ground for the radio to work as intended.

Also the antenna you have used is degined to have a ground plane also. So it might not work at all as it is in your current desing.

https://www.infineon.com/dgdl/Infineon-AN91445_Antenna_Design_and_RF_Layout_Guidelines-ApplicationNotes-v09_00-EN.pdf?fileId=8ac78c8c7cdc391c017d073e054f6227

Regards,
Jonathan

RE: low power wearable electronics.

Priyanka — Tue, 16 May 2023 05:27:46 GMT

Hi,

Jonathan is on leave and I will be taking over the case. Please expect a slight delay as it is the vacation period this week and we are a bit understaffed at the moment. Thank you for your patience. 🙂

-Priyanka

RE: low power wearable electronics.

LoPow@ — Thu, 11 May 2023 15:54:37 GMT

The main reason is cost. If we used multiple layer pcb then we have to add vias for connection and this will increase the cost of fabrication for revision one. Another is, for early fabrication we used single layer pcb.

RE: low power wearable electronics.

JONATHAN LL — Thu, 11 May 2023 13:52:23 GMT

HI,

There are a couple of big issues here that will cause problems for the operation of the nRF52840 and they can all be solved with adding a second layer to the PCB. The RF capabilities of the device will be poor.

Is there a specific reason to why you only want to use a single layer?

Regards,
Jonathan