Flash a-ah // He’ll save everyone one of us
Our #1 objective for this week is to find the components we will use in our project. Basically, we have to find: a micro controller, a BLE chip (possibly integrated in the MCU), some memory and battery. For the micro controller, we already have a favourite (nRF51822), however we need to look for outsiders. I listed some possible competitors yesterday, and now I have to compare them. About the battery, Adele made some good research, I’m sure she will tell you everything soon.
Concerning memory, we discussed a lot about this subject with the teachers on Wednesday. They had advised us to use a FRAM, which is designed to consume a little energy. However, when I looked for FRAM modules, I found out that this technology was extremely expensive (about $15 for 2Mb). So the teachers told us to investigate the Flash technology (now you have understood the title of this post). And a Flash module we found was not so energy intensive, and above all extremely cheap (about $3 for 64Mb). However it was not available anymore, so I looked for other products of the same family and I found the same chip with a 32Mb storage capacity (AT45DB321E). Eventually, we have a champion!
And last but not the least, I kept on my STM32 lab and now all the semaphores, interrupts and events work all together! Two lessons to be learned: conditional variables must be used with mutexes (and never alone! It doesn’t work! One can spend hours on that problem figuring out why the hell nothing works! I know this! It happened to me!) and semaphores are not that bad. In the end, I can switch on and off my led with a button (yes, I know, three days to light a led…). Next item on my to-do list: change its intensity with a potentiometer.
May the force be with you!