The 8-bit processors, in particular, have gone through slow, incremental changes over the years: from 12-bit, to 14-bit, to 16-bit program word sizes, with each bump adding more address space, new instructions, and a bit more stack space. The SAM D10, in particular, is the only Arm part I’ve ever seen this feature in – and it’s fantastically useful – even if their notation is a bit heavy-handed. Since MCUs rely on setting, clearing, toggling, and inspecting bits in registers, it’s convenient for the compiler and header files to provide methods for setting and clearing individual bits (and preferably bit ranges) inside registers – even if the architecture doesn’t support atomic bit instructions. These header files have zero documentation, no predefined bit offsets, and no bit-addressable register definitions. Even more puzzling is why there are no bitfield register definitions for the tinyAVR or megaAVR, even though the architecture clearly supports bit manipulation. You get every register name and description, with every bit described in the same detail as in the official documentation. This is the route Silicon Labs, Texas Instruments, Infineon, NXP, and Microchip go (though again, the first three provide much better documentation).

Consequently, I really enjoyed the MSP430 (and all Texas Instruments) LaunchPad boards. Regardless of what marketing departments think, dev boards should be free of extraneous sensors, buttons, LEDs, or anything else that a user can easily breadboard. It’s 2017 – storage is basically free. As always, it’s best if you use one pin to anchor and position it. In our prototype, a microcontroller is used to output 3.3 or 0 volt DC power for changing the operating state of four PIN diodes. This is one difference between the chargers that is visible externally if you slide the power plug off the charger. A single satellite dish may produce 2, 3, 4 or more coaxial outputs, each one carrying a different signal. This RLC Electronics’ Standard Size Coaxial Switch is a single pole, two position type providing extremely high reliability, long life and excellent electrical performance characteristics over the frequency range of DC-12.4 GHz. This instrument is a swept receiver that displays an out put on an oscilloscope screen that is amplitude vs frequency, so a single signal shows as a spike. XC8 beats out Keil C51 by tacitly duplicating any function that ISRs call into, eliminating the ISR reentrancy problem.

If you leave the feedback resistor out of an op-amp circuit, it operates like a comparator, but you shouldn’t use op amps to perform comparator functions except under limited conditions. This is a serious problem when porting large stacks built for other compilers, like GCC. As mentioned with Keil C51 above, the big problem is reentrancy – when a function attempts to call itself (i.e., recursion), or when an ISR calls the same function it happened to interrupt. The PIC18 was the first core for which Microchip supported C programming – though Hi-Tech had already developed a Keil C51-like compiler for the lower-end devices that lacked a proper stack. Like Keil C51, XC8 will reuse certain RAM addresses to hold local auto variables and function parameters. I kind of like it, but it’s pretty heavy, and I think if I used the architecture more, I’d prefer the Nuvoton approach. Having said that, you think they’re going to be great until you try to put them back together again. I think a dev board should have a row of jumpers that allow you to completely disconnect the target from the debugger. In terms of overall form factor, I’ll allow my personal preferences to gush out: I love dev boards that integrate a debugger and a microcontroller, with nothing more than break-out pins.

This works well, and is often more efficient than a stack-based approach simpler compilers can use on more advanced hardware. Microchip produces microcontrollers of three basic designs: an 8-bit, a 16-bit, and a 32-bit. The XC8, XC16, and XC32 are the current compilers in their collection that target each of these, respective. These are quite different processors and, under the hood, these are quite different compilers. Analog sources are well supported here with a trio of line-level RCA inputs and a separate MM phono input for those who will want to connect their turntable. GCC does. No optimization setting will fix this behavior, and because function calls are expensive on the 8051, this has dramatic performance implications. Here, these auto variables – which should be unique to the function’s execution – will be at the same address, thus causing possible corruption. None of the 8-bit PIC parts have a usable stack to store variables. Eventually, Microchip acquired Hi-Tech, and combined these two disparate products into XC8, which covers all 8-bit PIC devices.