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[Little Brosers] SoC choice

Here come the end of the third week of ROSE and the Little Brosers project keeps evolving!

For the past week, we have been designing the project based on a approximative idea for the SoC we will use.
We knew we needed a SoC including at least on-chip BLE and some hardware cryptographic blocks like AES and random number generator. The SoC choice should also be conditioned by the chip’s consumption.

Eliminating candidates

First choice was the NRF52840 from Nordic with its “ARM CryptoCell-310” providing a lot of security features that we wouldn’t have to implement in our software. The full description is available here. Unfortunately, this chip is not easily available right now and its consumption could be a problem if placed in a Drop.

We also considered the DA14681 from Dialog Semiconductor with the same kind of features but we’ve been informed that Dialog Semiconductor’s SoCs use to cause problems during implementation and its consumption would also be incompatible with our needs.

The five remaining SoCs

The remaining SoCs we had in mind were the NRF52832 and the NRF52810 from Nordic. Also listed are the QN902X and the MKW31Z from NXP. Finally, one of Cypress Semiconductor’s SoCs could be eligible, the CYW20737 . All of those SoCs have an associated DevKit and SDK.

The main difference between Nordic, NXP and Cypress is the presence of Bluetooth 5 in the Nordic chips. However, even if Bluetooth 5 makes our project ready for the next ~5 years of Bluetooth technology, we won’t take advantage of its higher throughput and longer range because less than 5 main stream smartphones feature Bluetooth 5 for now. Thus, the Little Brosers project will use BLE from Bluetooth 4 standard (even if it includes Nordic chips) in order to be compatible with the most of the smartphones out there.

How to choose the winner ?

The NRF52810 is basically a NRF52832 with less GPIO, PWM, RTC, TIMER and bus protocols. The RAM/flash capacity is also shrunken and NFC, I2S and the low power comparator have been removed. Thus if we go for the NRF52832, we will switch to its little brother only if we realize that the NRF52810 can run our code flawlessly with its reduced memory capacity.

On the other hand, the NXP and Cypress chips are quite similar from each other and for now we can’t decided which one we would pick if we only based our judgement on hardware.

Then comes the manufacturer’s SDK. This is gonna be my main research subject for the next days to determine which SDK will make our development flow easier and therefore, will help us finalize our SoC choice.

 

Stay tuned !

 

Antony Lopez

Antony Lopez

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