10 years, 3 months ago.

Isn't the range of bluetooth limitted compared to some other options? Or is the idea that the receivers location is used to track the location of the livestock? (Wouldn't you need alot of receivers? And you retransmit then with something else?)

I would assume you want for the devices on the livestock and for the re-transmitters a low-energy solution also? A core M0 will be the most logical solution. I have looked only a little bit into Nucleo energy consumption in deepsleep, but from what I measured IIRC I wasn't really impressed (probably due to the code base). But how much that matters also depends on the consumption of the rest of your system.

So you are going to need to figure out which requirements those devices have to meet exactly, and I don't know how much RAM/flash you are going to need for your code. The LPC812 is small and low power (https://mbed.org/platforms/NXP-LPC800-MAX/), maybe a bit too small and low power though. LPC1114 is also quite small (if you don't take the DIP package), waking it up from deepsleep with a timer isn't ideal, but a library exists which should work. And one where you might start your considerations is the KL05Z (https://mbed.org/platforms/FRDM-KL05Z/). Very small and low power, and more powerfull than the LPC812. If you end up needing larger devices you can either look at the LPC11Uxx series, or in the case of the KL05Z you can upgrade to one of its larger family members.

This is all assuming with small footprint you mean of the IC, where you want to make your own PCB. Otherwise have a look at: https://mbed.org/platforms/?form-factor=6. In which case you end up either with the LPC1114, LPC11u24 or LPC11u35.