PIC32 starter kit impressions

I got PIC32 starter kit today. Here are some impressions:

- Comes with eval version of C32 C-compiler with 64KB code size limit. C32 is actually called C32-gcc, so it's a gcc derivative. The source is on the website, but who knows if it's recent or complete.

- Hardware debugging (breakpoints, goto cursor) works in MPLAB on this little board, but I found that sometimes it gets into a mode where it thinks that breakpoints are not supported: "breakpoint limit for hardware is 0" in the breakpoint dialogue. This is fixed if you restart MPLAB. Anyway, you can view both assembly and C source during single-stepping. It's pretty nice.

- You can DBPRINTF over JTAG (and also DBGETS). It's very slow. It was not documented that you had to add a define to make this work for new projects (-DPIC32_START_KIT- add the define in Project->Build Options->Project->C-compiler->Macros). The debug I/O library is not part of the main library- it was just a db_utils.a file (no source) in the StartKitTutorial directory (the "hello world" program).

I had to copy it to the timer interrupt demo program that I wanted to try to get it working. I then had to replace all the UART I/O calls to debug I/O calls. There is no UART interface on the starter board, so they must be designing these demos for some other board (actually they are labs for a course- maybe FAE or early customer training?)

One annoying thing about this form of JTAG I/O (which is not unique to PIC)- it's not a real serial port. When you call DBGETS, a window pops up in MPLAB for you to type a string. This is a modal window, so you can not actually halt the debugger when it is up. So don't put DBGETS in a loop! There is no way to poll for keyboard input. When the DBGETS is waiting for input, the CPU is basically break-point halted, so interrupts stop running.

- This is how you make interrupt handlers:

void __ISR(TIMER_1_VECTOR, ipl2) my_handler(void) { mPORTDToggleBits(BIT_0); // Blink a led mT1ClearIntFlag(); }

And that's about it (set up the timer and EnableIntT1). You do not have to explicity write the my_handler address to a vector, the compiler just does it.

- The IDE needs a little work. There were some screen update glitches when I closed various windows. It core dumped when switching projects. The manual for the C-libraries (particularly the peripherals) is missing.

- On the other hand, things did generally work. You basically hit F10 to compile and F9 to run. It prompts you for downloading the code to the board.

- There are compiler settings for making compressed MIPS 16-bit code (like the ARM thumb code). Both worked. Last time I used MIPS, there was no 16-bit option.

Some notes about the PIC32 CPU:

- Someone complained that the chip has only 16-bit timers: this is not exactly true: timers can be paired up to form single 32-bit timers.

- There is a RTC clock generator (and an RTCC block) on the chip with pins for a 32 KHz crystal.

- There is support for some kind of external trace buffer on the CPU. You must have to buy some special ICE to make use of it.

- The code examples include HTML server on a TCP/IP stack, but they need a board with Microchip's ethernet to SPI interface chip.

/*  jhallen@world.std.com AB1GO */                        /* Joseph H. Allen */
int a[1817];main(z,p,q,r){for(p=80;q+p-80;p-=2*a[p])for(z=9;z--;)q=3&(r=time(0)
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Joseph H Allen
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can you comment on the power consumption of these devices? All I saw on th family datasheet was TBD for all current ratings.

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Hi, sorry about the multiple sends - unfamiliarity with this setup is m excuse! Nice post. I've ordered a PIC32 starter kit and look forward to having play with it in the next week or two. I'll feed back any points additiona to those already posted if and when I find them. I'm new to MIPS32 code s it should be fun. Regards, Joe Brown.















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Allen */



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