How to start off with ARM processors?

Question

Is it advisable to directly start off with the datasheet and user manual of an ARM processor for a newbie or first get an idea about the ARM world and then go ahead?

Answer 1

When I begin with a new (to me) technology, I start by locating as many data sheets and application notes as I can and just reading them straight through. The first goal is to get up to speed on the jargon (and names of the players) unique to that technology.

With ARM, I'd start with www.arm.com, and their documentation at the ARM Information Center.

Update: I would also dive in to one or more manufacture's product lines, including a reading of at least one family programmer's manual. If your project plans are firm enough that you know what specific ARM CPU is going to be used, then you can get away with focusing on that specific model and its close relatives. If you are looking to get familiarity with the ARM so that you can choose the CPU to be used in project, then sampling a broad array of families is almost certainly the best plan.

There is a big list of ARM technology licensees. Of these, a few makers have products (based on the CORTEX-M3 flavor of the ARM core) that IMHO stand out for deep embedded systems applications.

My company has projects underway based on the STM32 family from ST Microelectronics. This family has a lot of on-chip peripherals with functionality that will be familiar to anyone coming from the 8051 world, or from the PIC world, and has sufficient FLASH and SRAM on the chip to make external memories optional.

I have heard a lot of positive things about the Stellaris family from Luminary Micro. It too looks like a good fit to a number of embedded platform needs.

Given the current price points of entry-level evaluation boards, I would strongly recommend picking up one or more for chips similar to your anticipated target application niche. A board with a small LCD, accelerometer, a couple of LEDs a button or two, access to the uncommitted GPIO pins, a built-in JTAG USB interface, and a complete GCC-based cross development tool chain can be had for the STM32 (for under US$40 in 2009, but that model is discontinued) in the US$100 ballpark, for example.

Similar packages can be found for many of the other ARM core based products.

Another way in which ARM is found is as the CPU core in a system on a chip. Quite a few SOC vendors are licensing an ARM CPU to put on their silicon alongside their dedicated hardware. I have seen video compression chips, network chips, firewire to ATA adaptors, and USB devices built this way, and that is only a sampling from published articles and press releases I happen to recall off the cuff.

Update 2, 2013: A very accessible entry point to a "typical" ARM-based SOC family can be seen in the Raspberry Pi and the various Beagle family boards. Both are aimed at experimenters and hobbyists, both use SOCs with ARM cores and additional resources such as video and audio capabilities, and both run linux out of the box.

There are also a rich variety of system on a module makers providing a mezzanine board containing a complete bootable system for mounting on a custom board providing the power supply and I/O connectors required for a specific embedded system. One such vendor is Gumstix. The Gumstix AirSTORM provides Wi-Fi, Bluetooth, DRAM, NAND FLASH, and a TI OMAP3 ARM SOC. A suitable carrier board can support either an LCD panel or HDMI, 10/100 ethernet, USB host and OTG, and line-level analog audio connections, along with access to a variety of additional GPIO pins and on-chip peripherals.