32k crystal install and test

[pabigot 355]

2) low power (it is all low power lol)

 

Use of the crystal actually increases power draw slightly (sub uA, but at 100 nA it's relatively significant), so for ultra-low power (on 2xx devices) where timing is not critical it's better to use VLOCLK. I believe but have not reconfirmed that if the crystal is installed but not active, the power is about as low as if the crystal was not installed. For some power results, see BSP430's Application LPM page. (Edit: this page suggests I believed that populating the crystal does affect power consumption even when it is not used.)

 

On 5xx chips, especially FR5xx, there are cases where you cannot achieve the lowest power modes without a crystal.