Introduction and Disclosure

When the nRF52 series was launched by Nordic Semi back in 2015 https://youtu.be/HQlIcQH9JPM , the flagship nRF52832 was considered to be the fastest and most featured Bluetooth SOC, having an ARM Cortex M4F processor running at 64MHz in a very power efficient package.

The nRF52840 was its bigger sibling https://youtu.be/Ezno0u9zCmo , with availability announced in 2018. It doubles the maximum transmit power (from 4dBm to 8dBm), doubles the flash (from 512kb to 1024kb), and quadruples the ram (from 64kb to 256kb) while still being very power efficient. Aside from that, it also contains a built-in LDO and configurable DC-DC step down that allows it to receive a wider range of voltage (from 1v8 to 5v5) and has native support for USB.

Key features

• 64 MHz Cortex-M4 with FPU
• 1 MB Flash, 256 KB RAM
• 2.4 GHz Transceiver
• 2 Mbps, 1 Mbps, Long Range
• Bluetooth 5, Bluetooth mesh
• ANT, 802.15.4, Thread, Zigbee
• +8 dBm TX Power
• 128-bit AES CCM, ARM CryptoCell
• UART, SPI, TWI, PDM, I2S, QSPI
• PWM
• 12-bit ADC
• NFC-A
• USB 2.0

https://www.nordicsemi.com/Products/Low-power-short-range-wireless/nRF52840

I’ve mostly worked with the nRF52832, programming it via Espruino https://www.espruino.com/ and it’s been a really great microcontroller. However, my programs have been getting larger and larger, and instead of getting a spi-based flash chip to augment the program storage, I thought I should try out the nRF52840.

Which is why when Element14 announced a road test Panasonic PAN 1780 Bluetooth LE Eval Kit  featuring the nRF52840, I couldn’t sit by idly. I immediately sent in my application and fortunately, I was selected to be one of the road testers. Today, I received the PAN1780 Evaluation kit by Panasonic Industry.

Unboxing and Initial Impressions

Experience

I was sent the kit through UPS, and even though the sender was from Chicago and I currently reside in Kuala Lumpur, delivery took less than a week. In fact, it was a day earlier than the predicted receive-by date. I’ve always had great experience with UPS even during the covid pandemic and this time was no exception.

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Road Testing The PAN1780 Evaluation Kit (part 1) - Unboxing and First Impressions

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The package arrived in a nondescript brown box with some eco-friendly paper buffer along with the product itself. The product packaging itself was quite bare; just two anti-static bags containing the evaluation kit and an NFC antenna. There were no paper manuals, just a slip of paper reminding the user that there may be penalties for improper disposal of electronic waste.

In front however was a sticker with some information on the part number (ENW89854AWKF) and the contents (2x PAN1780 Eval-Board). It also has QR code and some plea to scan it, or alternatively visit a URL for further information and technical documentation. Scanning the code does give the same URL as was printed below it in plain text.

Quality

The units themselves were just a little smaller than an Arduino UNOArduino UNO, and came with a rigid, credit card-sized NFC antenna. Interestingly, the antenna wasn’t on a flex pcb like the ones you’d get with the Nordic dev kits, but rather on a tough multilayer pcb. You get the feeling that this antenna was made to last for a very long time.

Here is the included antenna, as well as the flex PCB antenna included with the nRF52 DK.

The eval kit was mostly SMD with the only through-hole parts being the jumper pins, momentary switches, male-female header pins, and the micro-usb sockets. It doesn’t look like any of the solder joints were made by hand, but the underside (where the through-hole solder joints are) had some thin layer of (possibly?) flux residue that is easily wiped off.

Just like the antenna, you get the feeling that even if this is just an eval kit, you can install this as is in an industrial setting and it wouldn’t look like it was out of place. I was especially impressed with the male extensions at the bottom of the board; in my experience these would usually be made of flimsy material, but in this case Panasonic Industry either coated the pins with solder or used a much tougher, not-so-easily-bendable and thicker metal (or probably both).

Completeness

While the package itself was quite bare, it contained the necessities. The NFC antenna was especially a nice piece of hardware. All of the jumpers have been installed in the correct places according to the online manual, and there aren’t any loose pieces inside the box.

The kit doesn’t provide micro-usb cables although that is probably expected, as everyone probably already has one or two (or too many) lying around, and if by some reason they don’t have one, they can easily source it from a local shop.

I was expecting the online resource at https://pideu.panasonic.de/products/wireless-modules.html (as printed on the QR code and the sticker) to link to the missing documentation and manuals, but found it as bare as the package I received. It took a moment to figure out that this page was just a gateway for the EU and the NA specific sites, and that the stuff I was looking for was in https://industry.panasonic.eu/devices/wireless-connectivity (that’s the EU link; the NA link goes to all of the offerings that Panasonic Industry has and it can take some time to drill down to the information specific to the PAN1780). It would have been nice to have the sticker print the QR Code and links specific to the evaluation kit, rather than to the marketing materials and have the user click through menus just to download datasheets.

If you’re following along, the page specific to the PAN1780 is at https://industry.panasonic.eu/devices/wireless-connectivity/bluetooth-low-energy-modules/pan1780-high-performance-and-long-range

Quick Comparison to Other Boards

nRF52840 boards, from top left: PAN1780 eval kit, Waveshare nRF52840 eval kit, Adafruit Clue https://www.adafruit.com/product/4500 , Arduino Nano 33 BLE Sense Arduino Nano 33 BLE Sense , nRF52840 DonglenRF52840 Dongle

nRF52832 boards, from bottom left: Espruino Pixl.js https://shop.espruino.com/pixljs , Espruino Puck.js https://shop.espruino.com/puckjs , nRF52 DKnRF52 DK

Here's the PAN1780 eval kit and its NFC Antenna, together with the Arduino UNO and the nRF52 DK.

Form Factor

Breadboard friendliness

When I first saw pictures of the PAN1780 evaluation kit, I thought “oh they are using the Arduino Uno R3 form factor, I should be able to use the shields I have for the road test.” Disappointingly, it wasn’t the Arduino form factor even though the eval kit had a similar size.

It does have male pins extending towards the bottom, so I thought maybe this can be used for prototyping via breadboard. Again, disappointment reared its head as the pins were just too wide for the usual 5cm breadboards; I had to combine two breadboards and have the eval kit straddle the power rails for it to fit. They do call it a daughterboard in the documentation, so most likely it was designed to plug into some larger test bench.

Unfortunately, the board is just too wide to fit on a single breadboard.

You would need to join two breadboards together and have the eval kit straddle the two in order to have enough space. This might be an issue if (for some reason) you don't have enough breadboards.

Extendability

What I do have in quantity however, are those cheap single-sided 5x7cm protoboards. Fortunately, the pins of the eval kit are on a standard 0.1in spacing and I was easily able to make a base and a shield using some female headers and some long pin male headers, respectively. This seems to be how the evaluation kit was designed for when prototyping connectivity with sensors and other supporting peripherals.

Here's my attempt at trying out a baseboard, and a "shield" for the PAN1780 eval kit. While I took the pictures like this, I'll probably turn the boards around so as not overlap the "keep out" area of the module's chip antenna.

And here's one of the ideas I have with the bottom baseboard; aside from adding components directly connected to the gpio, it can also become a holder for a battery, making the whole kit portable.

I do feel that there was a missed opportunity here with regard to support for commercially available, pre-packaged add-ons. There are many available sensors prepackaged for the Arduino Uno R3 form factor, and if the Arduino form factor is a no-go due to the unconventional 0.05in spacing on one of the gpio rows, there is the Arduino MKR pin layout, or the Adafruit Featherwing pin layout (both of which have a considerable following).

Either of these two layouts have support for a large number of sensors and peripherals in their ecosystem, and have the advantage of being already widely and commercially available for an even quicker prototyping. That said, it's not that much of a big deal since, as I've shown, it's not that difficult to add your own baseboards or shields.

Suitability as an Evaluation Kit

Evaluation kits are usually designed so that the engineer can easily configure the product to be evaluated easily and without having to wire up components themselves. Most of the time they are not intended to be used as part of the final product, which is why they are often designed with maximum configurability in mind as opposed to efficiency in routing and component placement. Evaluation kits are also often used to quickly jumpstart a user with the software required to drive the main product as everything is expected to be ready and "just work" when plugged in.

Pins brought out

The nRF52840 has a total of 48 gpio, but the PAN1780 has pins 0.00, 0.01, 1.00, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.10 and 1.11 not brought out, or not connected to a peripheral (or at least I couldn’t trace them to their connection on the schematic).

Another issue is the lack of male ground pins on the top side of the board. There are a number of peripherals like the j-link OB and the ftdi USB to Serial pins that would need a common ground with the interfacing module. Having a ground pin nearby (or at least a few of them in a cluster that's clearly marked) would have been more convenient.

Unlike the nRF52840DK the PAN1780 Eval kit does not have a built-in QSPI for additional flash storage. This might be something to consider when evaluating the platform as QSPI is one of the interfaces headlining the nRF52840.

There is also no 32kHz crystal connected, which means there is no low frequency clock source available and you’ll have to use a synthesized low frequency clock source for your applications. I also don’t see anything in the schematic that indicates the crystal pins are brought out if an external crystal is to be added.

Configurability

A jumper system is used to enable and disable certain connections. For example, the nRF52840 has two modes of powering: the normal voltage mode, and the high voltage mode, and there are jumpers that would link certain voltages to the corresponding input on the mcu.

One issue I've found though is that some of the jumpers (particularly JP7 as was installed by default) can be difficult to adjust as they are too close to the female headers, or to other pins. I needed to use some tweezers when I had to move JP7's jumpers for example.

Silkscreen

Among some of the complaints thrown against the new Arduino Nano series is that the pin identifier silkscreens are at the bottom, rather than at the top. This makes it difficult to use the new Nanos in a breadboard since the silkscreen is underneath. The PAN1780 evaluation kit has the same issue: the pin identifier silkscreen is at the bottom, rather than at the top.

Here's a picture from the top, showing the silkscreen labels.

And here's a picture from the bottom, again showing the silkscreen labels. I have moved the sticker that was covering the test points (they were unlabeled, and I'm not yet sure what they are).

This probably isn’t as much of a big deal as with the Nano, since we are unable to use the kit with a breadboard as efficiently anyway. It does however still cause minor annoyance, at least in the prototyping stage where you just want to plug in a sensor on top using some DuPont wires without bothering to design (and etch) a PCB.

I suppose that in a professional environment, where dozens of engineers will have access to the same eval kit as well as sensors adapted to this form factor, this problem is minimized. In a maker or hobbyist scenario though, it may increase the chances of mishaps when accidentally plugging into a power pin instead of a gpio.

Another issue (which is likely due to the density of the components on the board) is that while there are generally identifiers, the specific jumper pins to various external components aren’t labeled. For example, the pins for the USB to Serial functionality (JP7 and JP10) don’t mention which of the pins are TX, RX, CTS, and RTS. It also isn’t immediately obvious in the documentation to which pins of the nRF52840 TX, RX, CTS, and RTS are actually connected to; you’d have to ether consult the schematic for that, or look underneath the board for the silk screen (it’s P0.6, P0.8, P0.7, and P0.5 respectively in case you’re wondering).

Bare module

Companies like Panasonic Industry, Raytac, Minew, etc. manufacture premade modules that don’t contain just the microcontroller, but supporting components such as capacitors, crystals, and especially an antenna. While anyone can probably get just the plain nRF52840 for cheaper and place it themselves on a PCB, there are advantages to getting a premade module from a reputable manufacturer. For example, radio antennas are notorious for their difficulty in tuning for maximum reception performance. Having a manufacturer produce a module with a built-in antenna that's already tuned to desired characteristics means the user does not have to worry about this part of the product design.

The PAN1780 module itself (outside of the evaluation kit) is really small. Unexpectedly small that is, and a bit surprising how such a tiny chip can be so powerful. The size makes it really convenient for embedding the module into a product; however it does have its own drawbacks for a hobbyist.

For one, the BGA layout makes it difficult to manually wire up a one-off on a protoboard. Not only that, those pitches are really tiny. While it speaks volumes of the amount of precision Panasonic Industry has in their manufacturing line, this kind of precision isn’t commonly available to hobbyists.Then again, this module likely isn't targetted towards the hobbyist who's looking to wire up a bare module by hand.

Here's a picture of the MDBT50Q, Waveshare nRF52840 module, and the PAN1780. You can see that the difference in the size of the PAN1780 against the other modules.

Price / Value

Competitors

In terms of evaluation kits, I have two that are similar enough to be comparable: the Nordic nRF52840 DKNordic nRF52840 DK and the Waveshare nRF52840 eval kit https://www.waveshare.com/nrf52840-eval-kit.htm

The Nordic nRF52840 DK is a development kit from the chipmaker itself, and they do their very best in bringing to light the chip’s capabilities. All gpio pins are brought out, and there is an onboard Segger j-link programmer with debug out functionality enabled (which means you can use the DK to program a Nordic chip other than the one that is on the board).

The Waveshare nRF52840 eval kit on the other hand comes at half the price of either the Nordic nRF52840DK or the PAN1780 eval kit, but does away with the onboard j-link programmer, meaning you’d need to get your own programmer in order to work with that eval kit. Just like the DK, all the gpio pins are broken out, and it has this useful jumper system where onboard peripherals (like LEDs for example) can be reconnected to a different gpio, making it really versatile.

However, if all you wanted was an nRF52840 and you didn’t care much for the number of gpios exposed, nor the inclusion of a programmer, the Nordic nRF52840 DongleNordic nRF52840 Dongle might just be right up your alley. It’s just around the size of a common USB thumb drive, and contains a DFU bootloader that sidesteps the need for a separate programmer, making it really compact and portable.

Addons

Surprisingly, the PAN1780 Evaluation Kit turns out to be a much better value compared to the Nordic nRF52840DK. Not only can you get the PAN1780 cheaper while getting almost feature parity, you also get a separate USB to Serial FTDI chip separate from the j-link functionality. The nRF52840DK only has a virtual COM port, and does not have a dedicated chip for serial communications.

This is especially useful for cases where you’d want to try out UART communication with the chip, but don’t want to do it through the Segger bridge (for example, when testing close-to-production code).

Here for example, is a bare module running the Mbed OS ble cli example app (see ARM Mbed OS on a Bare nRF52840 Chengdu Ebyte Custom Target  for the blog post about this). I had to use an external FTDI adapter to facilitate the serial communications; the PAN1780 wins in this regard because it already includes the FTDI chip.

Speaking of j-link, while there was no explicit mention of a debug out feature, the fact that the j-link and the swd pins of the nRF52840 are bridged together via jumpers mean you are able to use the onboard j-link device to program a chip other than the one on the board (and vice versa; you can use an external programmer to program the nRF52840 onboard).

Here for example is a bare nRF52840 chip being programmed via the SWD using the PAN1780 eval kit's j-link programmer. See more about the bare nRF52840 chip on my e14 blog posts about it: Trying Out the Chengdu ebyte nRF52840 Module You don't see it here, but the common ground is connected to the underside of the eval kit; as mentioned previouslt the top side doesn't have clearly marked ground pins that can be easily used for these tasks.

While using an eval kit's onboard programmer is frowned upon when programming chips in commercial quantities, if you are a hobbyist or a maker that would like to dip their toes in the ARM ecosystem, having access to a proper SWD programmer is a must. The cheapest j-link that Segger sells would be the j-link edu minij-link edu mini, which already costs about half of the eval kit and still isn’t allowed to be used for commercial purposes.

Oftentimes the advice for makers would be to get one of the Nordic development kits as that includes a j-link debug out capability (again only to be used for educational or personal purposes). The PAN1780 Evaluation Kit has this advantage as well, and the smaller form factor might also be an advantage (the Nordic development kits were notorious for being really large when all you wanted was to use its onboard programmer).

Here's a screenshot of the j-link configurator while upgrading the firmware on the j-link OB of the PAN1780 eval kit.

Note however that unlike the nRF52840 DK's j-link OB, the one in the PAN1780 eval kit does not create a disk drive that you can drag and drop hex files onto for flashing. This means that it's not immediately compatible with Mbed OS; you'd need a two step compile-upload procedure in that case.

On Windows 10, the j-link creates two COM ports (CDC and Serial) as well as a USB device with the "J-Link driver" label.

Summary and Next Steps

When working with Nordic products, the usual recommendation is to get one of their development kits (in this case the nRD52840 DK) as it has most of the tools and peripherals you’d need to work with the ecosystem. The Panasonic PAN1780 Evaluation Kit however is proving to be a serious contender; not only is it cheaper while maintaining almost perfect compatibility with the nRF52840 DK in terms of LED, button, and UART pinouts, but it also has additional value-add peripherals like a micro-usb port connected directly to the chip, a separate FTDI for UART communications, and a tough, high-quality NFC antenna included.

Next up, we'll take a look at the documentation and software, and will be trying out some of applications mentioned in that documentation.