Looking at a wristband that has the nRF51822 for a commercial project

[Noelle Brown]

1.Size of EPROM. Is it big enough for our program as well as our data file for the whole day?

2.How can we secure the EPROM so that no one else can overwrite our code or data file?

3.How can we use Accelerometer on the Wristband/Bracelet? Is there an API?

4.Have any other Nordic customers has done the following in Production mode (not Pilot or POC): a) Bluetooth connectivity to server b) Data transfer using Bluetooth c) What is the data transfer speed? d) EPROM datafile cleanup every day or multiple times a day e) What is datafile cleanup speed? f) Is there any limit on deleting and creating the datafiles in EPROM (like 100,000 read/write operation)? g) Can we load the Android o/s in EPROM and have it communicate with the chipset (or is eeprom too small or current Android too big?)

Thanks in advance

Noelle

[Ole Morten]

I can try to answer your questions, but I can't share information about other customers. Perhaps some of them would like to chip in with additional comments.

The nRF51822 has a 128/256 kB flash, that can be used for both code and data. If using the Peripheral softdevice that's 80 kB on a 256 kB chip, a typical application would leave almost 100 kB for user data. You can enable readback protection for the flash, denying all access over the debug interface. Take a look at the MPU chapter of the nRF51 Reference Manual for details on what this will deny.

An accelerometer can be accessed over any of the digital serial interfaces of the chip, which includes SPI, TWI or UART. There are examples of all in the nRF51 SDK.

Several wristbands have been made using the nRF51822, but I can unfortunately not share details about them. For data throughput calculations with the S110, you can take a look at this. The max number of erase cycles for the built-in flash is given as 20 000 cycles in the nRF51822 PS.

The ARM core in the nRF51822 is a Cortex M0, and it is not possible to run Android on such chips.

[Noelle Brown]

Ole - can you clarify your sentence...max number of erase cycles for the built-in flash is given as 20 000 cycles in the nRF51822 PS.

does this mean if we are storing data on the built-in flash, every time we write to it, it is considered a erase cycle OR

only when we transmit the data and completely erase the flash being one cycle ?

thanks