Diseño de beacon nrf51822- QFAC(DC/DC)

[ProtexFor]

good morning to all I wanted to ask if anyone has a design of nrf51822 where an external temperature sensor is used, to know how the connection to the chip is. Should I buy a sensor with an analog output or a digital output? What is the difference? Is this sensor valid to take the room temperature?Sensor Does anyone know how ADC works? I would also like to know how to implement an antenna, what do I mean by this? I understand that the reference design does not come with the design of the antenna, is this true? If it is correct, how can I implement an antenna for the development of the beacon with nrf51822-QFAC(dc/dc)? Another question is, how is the balun connection for nrf51822? Where does the balun connect, on which pins on the chip? With what software can I edit the PCB, to do the implementation of the antenna, the balun and the temperature sensor? I also need to make the copper island for each pin of the chip, so I have the possibility to program without removing it from the pcb circuit, can it be carried out? I hope I have been clear in the questions. Greetings to all.

[Jørn]

Hello ProtexFor

Unfortunately Nordic does not have any finished designs for this, however you might find some help in the hardware description of the Nordic Thingy:52 here, as it does have a digital temperature sensor.

How it is connected to the nRF would depend on the sensor you have chosen, typically you will either use the ADC to read an analog value, or SPI/I2C for serial communication.

Analog sensors generates a continuous voltage which represents the temperature measured. Typically you will measure it with an ADC.

Digital sensors convert the temperature measured into a number and transfer it through serial communication to the chip. Typically interfaced with SPI or I2C.

The sensor you link should work just fine with room temperature, as it can measure -40 to 125 degrees Celsius with a resolution of 0.015 degrees Celsius. It can run of 3.3 V, which is the same as the nRF51, this is ideal for interfacing the two. The sensor outputs an analog signal which represents the measured temperature. You will need to use the ADC of the nRF51.

If you are new to our products I recommend you look at our tutorials here on DevZone, as well as our Getting started infocenter page.

The nRF51 series has two documents which is of particular interest, the reference manual and the product specification, both are found here. The reference manual contains more detailed description of the hardware common to the 51 series, while the product specification is specific for the different chips (nRF51822, nRF51422 etc.).

ADC documentation can be found at page 164 of the reference manual here.

We have a Software Development Kit (SDK), which contains our Softdevice (Nordics Bluetooth Low Energy stack) as well as drivers, libraries and example code. The latest SDK released with support for the nRF51 series is 12.3.0, and is found here. If you want a newer SDK you will need to use the nRF52 series.

Documentation for the ADC hardware drivers from SDK 12.3 are here. Example for the ADC is found in the SDK folder under examples/peripheral/adc, documentation for the example is found here.

The reference design in the nRF51822 product specification (page 79 and out) does not have antenna. However the hardware layout designs for the development kits, and the beacon are available. The designs are made in Altium, and if you have that you can edit the files. If you don't, you can't edit them, but you can view them as reference using Altium viewer. The hardware files for the nRF51DK can be found under downloads at the nRF51 DK product page. The beacon hardware files can be found here however you will need a product key (obtained on purchase) to download them.

For more information on PCB designs see this post. More information on antenna design can be found here.

The nRF51 has 3 pins related to the RF output, ANT1, ANT2 and VDD_PA. ANT1 and ANT2 are the differential outputs of the radio, while VDD_PA is the radio power supply. Figure 35 (page 104 of the product specification) shows how the balun should be connected to the chip.

There are many software products for designing PCB, ranging from very expensive to open source. Nordics designs are made using Altium designer. Altium has several software products that can be of interest. Some free alternatives are Altiums Circuit maker (cloud based), Eagle (limitations on number of layers and PCB size on the free version) and KiCad (open source), however there are many more out there.

If you wish to program the chip directly, you can use the SWDIO and SWDCLK pins, along with a SWD programmer (such as the segger J-link edu). For more information on SWD see this blogpost, and here. These links are for the nRF52 series but it is valid for the 51 series as well.

If you have a nRF51 DK you can use that to program your custom board via P20, or the "Debug out" P19, see the nRF51DK user guide here, this post and as this post.

-----Edit in response to additional questions:-----

The nRF52 series is newer than the nRF51. I recommend reading the Migrating from the nRF51 Series to the nRF52 Series on the infocenter for more information on the differences between the two.

The nRF52 can be used to develop BLE products in the same way you can with the nRF51.

Just to clear up a misconception here, the SDK (Software Development Kit) is simply a bundle of software to help you develop your product on our chips, and you can download it for free from the Infocenter.

The nRF51 and nRF52 DK (Development kit) on the other hand are circuit boards with either the nRF51422 (for the nRF51 DK), nRF52832 (For the nRF52 DK) or the nRF52840 (for the nRF52840 preview kit) mounted on it. These kits will allow you to quickly start programming our chips via usb, and provide header pins for you to connect additional peripheral devices. The kits have a monopole PCB trace antenna, and can connect to your phone if configured correctly.

The beacon kit itself would normally not connect to a phone. The objective of a beacon is to simply advertise data, so that any passive listener can receive data from it. As such you would not connect and bond to it.

I recommend you take a look at the tutorials regarding Bluetooth Low Energy at the tutorials page, these will go into the basics of Bluetooth Low Energy.

Yes the balun connection would be identical. However as stated in the nRF51 PCB guidelines tutorial I linked to you above it is recommended you use the 2450BM14E0003 for QFN packages. Do note if you decide to go for the nRF52, you will not need a balun as it has a balun internally.

Best regards

Jørn Frøysa

[ProtexFor]

Hello Jorn Froysa. I thank you immensely for the answer. Let's go in parts: -Thank you for the data of the sensors, I have decided to buy that, and with an analog output.

• Yes, I am new, I just want to buy everything needed to develop the headlamp, the idea is to make a single order, since the shipping costs are more expensive than the products. -Download the manual and product specifications.
• Could the nRF52 be the most up-to-date version?
• Can you develop a headlight in the same way as with nRF51?
• I ask the antenna question and the balun question, since I will buy the SDK (as long as it is convenient before the nRF52), also buy the beacon kit, 5 chip nRF51822 - QFAC with corresponding components for each . "Is it all necessary?" Or with the SDK and chips with the necessary components is enough? I understand that the SDK can not connect to a smartphone, but the beacon kit does. It is true?
• As for the balun connection in Figure 35 on page 104 of the product specification, in the packet variation is CDAB WLCSP, is the same connection for QFAC QFN48? regards

[Jørn]

I have updated my answer above to answer your questions.

[ProtexFor]

Thank you Jorn. I had not noticed the difference between SDK and DK. With the nRF51 and nRF52 can you program nRF51822 to make a beacon? The goal of development is to know the distance and the ambient temperature. No matter the size of the prototype. regards

[Jørn]

Yes, all nRF chips can be configured as beacons. A beacon is simply a Bluetooth Low Energy device configured to transmit data without a specific receiver (Advertising). What distance are you trying to measure?