To Turn An ATtiny817 Into A 150MHz Counter, First Throw Out The Spec Sheet

One particular commonly reads a data sheet in just one of two strategies. The to start with is to consider each individual spec at encounter benefit, figuring that the engineers have taken every little thing into account and introduced every single number as the absolute limit that will avert the Magic Smoke from escaping. The other way is to toss out the details sheet and just attempt whatever you want, figuring that the engineers played it as safely and securely as probable.

The latter case seems to have been the enthusiasm guiding pushing an ATtiny way, WAY over and above what the spec sheet states is probable. According to [SM6VFZ], the specs on the ATtiny817 show that the 12-little bit timer/counter D (TCD) really should be restricted to a measly 32 MHz most frequency, earlier mentioned which just one is meant to use the counter’s interior prescaler. But by utilizing a 10-MHz precision frequency generator as an external clock, [SM6VFZ] uncovered that inputs up to a bit above 151 MHz ended up countable with 1-Hz precision. Earlier mentioned that place, issues commenced to drift, but that is still fairly excellent overall performance from a thing cobbled jointly on an eval board in a decidedly suboptimal way.

We’d envision this result could lead to some appealing assignments, considering that the undocumented limit for this timer puts it properly inside of selection of several beginner radio allocations. Even if it does not demonstrate handy, that’s Alright — just viewing how much points can be pushed is amazing much too. And it is not like this is the first time we’ve caught [SM6VFZ] persuading an ATtiny to do strange things, both.