In SX Microcontrollers, SX/B Compiler and SX-Key Tool, CCraig wrote:

OK, I need more help. Those unfamiliar with my project.

review: A GPS module piggybacked on Bean's SD data logger. (operates as a stand alone if need be). That unit (GPS/logger) and another (Keyboard/LCD) talk to a main unit SX28. Moving to SX48 or Prop? That's the question by the way.

Problem: In the main unit, I'm running dual VP UARTs. Well, one UART and one SIO. Works fine, thank-you JonnyMac! Now, I'm really going to need a Math Fpu. I don't know if I have the resources to add that inside the ISR. I think my ISR is running fast, so I think I can call it less often to give me more time, but...

Questions:
1. How do you calculate how much time you have left in the ISR. Do you look at the listing and count instructions? I tried SXSim and couldn't get close. I know I read something, but can't find it now.

2. 2 UARTs + 1 I2C master in the ISR is that possible? Even if I want to add another SX to offload some work, I'd have to come up with another VP UART for a total of 3 UARTs at 9600 baud.

3. Am I heading towards a brick wall at 90 miles per hour? (So I guess I'll be using the GPS for a 'X marks the spot' device.)(And does FTD deliver to GPS coordinates?)

4. Is it time to get out the PE kit and get to work? Where I probably don't need a math coprocessor.


I think I know the answer to #4. It seems like last month I was asking if it was possible to put two UARTs in the ISR, now I want more. I just need support and advise. I have it fixed in my mind that this project should use all SXs. Maybe this should be the project that forces me to learn the new platform.

Thanks In Advance, Chris

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