Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

JTAG wiggler clone for ARM microcontrollers

The Olimex ARM JTAG clone is well known as there are many schematics on the internet available. Circuits are straightforward and seem to be reliable. This adapter can also be set up to work with WinARM tools: obdremote and gdb/Insight-gdb. In the circuit, there is a critical part that needs to be considered – 74HC244 buffer IC. Family of HC support less than 4.8V if powered with 3.3V. But reality shows that Parallel port voltage usually is lower than 5V so that HC will fit. But of course, it is better to measure the HIGH state of parallel port pins. To be more sure, HC should be replaced by 74LVP244 or 74LPT244. These chips support 5.5V in entry with a 3.3V supply, but sometimes they are hard to find in the market.

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Debugging tools for ARM7

Usually, one solution of debugging is to run compiled code on a PC simulator. You can download a limited version of the instruction set simulator from Hitex for free. Of course, better simulators aren’t for free. More advanced simulators you can purchase at Keil. More advanced, I mean that there is the ability to simulate peripherals by additional scripting and so on. But again, simulators are virtual tools, and usually, it is hard to simulate real-world events. Once you face this problem, you are going to switch to real-world simulation using JTAG.

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