Today we discussed another alternatives for the microcontroler, given that the L151 is hard to find and the F105 consumes too much power. We came across the STM32F205 line, which seems to be the best option we found up to now.
This is called the Hi-Performance series of microcontrolers, yet they have a very low power consumption (199µA/MHz, lower than the L151). They also can go up to 120MHz, although we think that we won’t go that far to avoid excessive power consumption. They also cost very little, almost the same as the STM32L1 or just a couple euros more than the F105 equivalents.
We are just in discussion about the flash memory size. We noted that the programming challenge image had around 100kb, thus we ruled that, since our project will be something much more advanced, it will need much more memory. We want a microcontroler with a flash between 256kb and 1Mb, the cost being the other restriction here. Here we have three options:
- The STM32F205VCT6 with 256Kb of Flash, 100kb of RAM and costs 8€13. This is the cheapest option.
- The STM32F205VET6 with 512kb of Flash, 132kb of RAM and costs 9€65. This is the intermediary option.
- The STM32F205VGT6 with 1M of Flash, 132kb of RAM and costs 11€42. This is the option with greatest memory size.
Choosing a big memory size can be useful for early development to see how much memory we will use until the end of the project. Since the microcontrolers are pin-compatible, the “production” robots can use another model with less memory.
Another discussion is about the packaging of the microcontrollers. We will need more pins than the LQFP64 can offer, so we are considering using a µC with 100pins (all the three above are LQFP100).
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