It’s funny how a topic as apparently mundane as the DMA controllers on the STM32F2xx and STM32F4xx processors can be such a can of worms. I’ve already provided 2 postings on the subject, here and here, and now we have a third.
This one is a biggie. From what we’re seeing, it appears you can only [...]

Here’s the link to Part 1.
A very significant limitation with the STM32F4xx family (STM32F405 / 407 / 415 / 417) is that fully a third of its internal RAM is inaccessible to the DMA controller. Of the 192 kB of available RAM, only 128 kB can be accessed by the DMA. The other 64 kB, [...]

I’m not generally one to repost articles and links to articles – you won’t find much of that on my blog. Nor am I particularly pro-this or anti-that when it comes to technologies, brands, companies, etc. I have Apple products and non-Apple products. I’ve used various flavours of Mac OS, of DOS, of Windows, of [...]

The discussion around the STM32F2xx and STM32F4xx DMA controllers is becoming a bit too large for a single posting, so here we are with Part 2!
Clearing a DMA Interrupt
In theory this is very simple – in practice not so much. The documentation for the “DMA low interrupt flag clear register” (DMA_LIFCR) and the “DMA [...]

Some time ago I built a signal generator, which is a reasonably handy bit of equipment. But I was periodically frustrated with not having a suitable probe to easily inject a signal into a circuit. The standard BNC – BNC cable has its uses, but isn’t too great for that kind of thing. And a [...]

Recently I purchased a Class 10 SD Card from a major retailer. I was very excited – now I have a fast card for testing. Here’s my new baby:

Note the 10 in the part-circle indicating the speed. For those who don’t know, the “class” speed system for SD cards is very simple. It’s the write [...]

The STM32F2xx has a great SD Card interface. It’s a true 4-bit parallel interface, and in general it works pretty well. I have come across a few, fairly minor but still significant, considerations when using the interface that I thought I’d pass on.
Initialisation Sequence
Proper initialization of the SD card is important, because SD cards have [...]

I’m using the STM32F2xx DCMI port to receive data from an CMOS image sensor. There aren’t too many Cortex-M3 or M4 parts which have this ability natively; the STM32F2xx is a rare breed. It’s a very nice feature. Along the way I’ve learnt a few things about the DCMI port, some of which are documented, [...]

If you’re moving a bunch of data around, the DMA controllers are going to be your best friends. However they have their quirks and undocumented features. This post will describe what I’ve learned about them, and hopefully others can contribute if they can shed light as well.
Note there is also a Part 2 to this [...]

I’ve been doing a lot of work recently with the new ST processor, the STM32F2xx family. It’s a Cortex-M3 part running at 120 MHz. It’s a nice part, however I’ve lost a lot of time discovering, well, let’s not call them “bugs”, let’s instead call them “undocumented features” of the part. At the time of [...]