3 ms·
Do these give you decent performance DMA-able gpio and spi like you get even on a cheap rpi4? (I'm not claiming they don't/can't, just that it isn't immediately
by qhwudbebd 2y ago
Do these give you decent performance DMA-able gpio and spi like you get even on a cheap rpi4? (I'm not claiming they don't/can't, just that it isn't immediately obvious to me that they would.)
For example, spi is an easy hack to bit sample a digital level and stream the results into memory for later processing. You can effortless do this at 20MHz+ plus on an rpi4. When you want to stream multiple digital levels simultaneously (in sync), DMA on gpio is a nice generalisation. (Could perhaps abuse I2S inputs too, which might be present on a more generic x86 board?)
I always wonder about a nice PCIe board supporting good DMAable gpio/spi/i2c/etc on standard x86 machines. I'd probably pay a fair amount of money for a quality one. But it's a product I've never seen on the market. Bodging a USB gpio interfaces with one of the relatively low spec chipsets seem like a pale, inefficient and high-latency imitation.
Actually, given the RP1, maybe the rpi5 has slow/non-DMA gpio too? I haven't been able to check it out yet as these boards still don't have mainlined linux support and I'm not up for buying toys that don't. (Am I imagining it, or did they used to be a lot better at mainlining support for their boards promptly?)