SO IS THE DRO-350 AND THE 16F876 PIC REALLY A DEAD-END STREET?

Several reasons for the DRO-350 being at a dead-end are given. I discuss some of them below.

A compiler for the PIC series of processors is too expensive.

While the “Official” compiler from MicroChip, the compiler with which the original code for the DRO-350 was developed (Scott had access to it at one of his employers/clients/friends), is very expensive, there are several high quality C compilers available for as little as several hundred dollars. These compilers utilize the same libraries as the MicroChip compiler (the libraries are free from MicroChip).

Several hundred dollars is not pocket change to most of us, but not particularly out of line when you are talking about keeping the DRO-350 alive in it’s present state (i.e. price).

In addition, MicroChip offers a very sophisticated Assembler as a part of it’s free Integrated Development Environment.

I have one of the third party C compilers as well as the free PIC IDE. I don’t think there is anything that can be done with the MicroChip version that can’t be done with the third party versions. Mine (the C compiler) even has support for the various In Circuit Debuggers that are available from MicroChip and other vendors.

Moving from one compiler to another is not an trivial task, but again, when we are talking about extending the life of the DRO-350 for what is probably 1000’s of existing users, a bit of effort is worth while. Portability, not just for moving from one platform (computer type, MPU type, etc) to another, but also moving from one compiler to another, is one of the reasons we use high level languages like C.

The 16F876 is “maxed” out.

Yes, the 16F876 is stretched to the limit when it comes to memory. But there is a bit of room available, and certainly enough room to correct bugs. And if the software were made Open Source (it’s supposedly been made obsolete by the DPU-550 which offers Open Source software), there would be many hands that would gladly apply their effort and imagination to getting the last few drops of functionality out of the current MPU. This has already been done by members of the group who have disassembled the DRO-350 code to make changes.

Some of the results of these efforts were posted on the group until recently. These postings had to have been with Scott’s “blessings” since he controls everything that goes on with the group. (Every posting is reviewed by him before being allowed on the group.)

There is a replacement for the 16F876.

The 18F2525 is a plug in replacement for the 16F876 (the current MPU). You can unplug the 16F876 and plug in the 18F2525 without any changes to the circuitry of the DRO-350. As a bonus, you can replace the current 20mhz resonator with a 40mhz version and take advantage of the full processing power of the 18F2525. And if that’s not enough, the 18F2525 is reasonably priced. DRO-350’s with the new MPU could be priced about $5.00 more than the current version. Replacement MPU’s for existing DRO-350’s would be about $15.00.

But the 18F2525 is more than just a faster processor. It has over 3 times the memory space as the 16F876.

Again, the task of moving the software from the 16F876 to the 18F2525 is not to be taken lightly. But it can be done. One member of the group disassembled the DRO-350 code and converted the resulting code to run on the 18F2525. If the DRO-350 code were made Open Source the job would be that much easier. Again, not an overnight task, but with many hands, the job would be easier.

The group member who disassembled the DRO-350 code produced a combined lathe/mill version and posted it on the group. It remained there for a few weeks until shortly before the release of the DPU-550.

When you consider that probably 60% or more of the DRO-350 code is common to both the mill and the lathe versions (you read the scale the same way whether it’s on a lathe or a mill, you display the data on the LEDs the same way whether you are displaying data for a lathe or a mill, etc.), the increased memory capacity of the 18F2525 becomes more significant. All of a sudden, the practical results of the increased memory makes it seem like 4 or 5 times the memory instead of 3 times.

Enough for today – Be sure to post your comments, good or bad.

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