2.4 ghz WiFi ID

[Christopher4187]

I think that all you need to do is take a moment with a pen and a piece of paper and really think thru what you need. It sounds like a pretty complicated product if it requires USB, CAN, WiFi, RF-link and what not - but that's cool.

It's cool but it's becoming a huge headache. BTW, the RF-link I think I can replace with the wifi module. It's like everytime I look around for something to fit the requirements, I get excited but then figure out it's missing one critical thing. I could move over to MikroElectronika stuff because they have pic24 and pic32 stuff, but then I have to buy all new stuff and learn their version of Basic.

I don't follow here. Don't you need to redesign in order to add the RN-171 and your external UART chip?
On the 18F45J50 PGC and PGD are on PortB.6 and PortB.7 respectively - exactly the same place as on the 18F4550 you're currently using. What do you mean by dedicated?

I was planning to make the RN-171 an add-on board with SPI connections on the header. The 18F4550 has dedicated ICSP pins. I don't use PortB.6 or PortB.7 for ICSP. You see how the 18F45J50 has N/C on pins 12, 13 and 33? The 18F4550 has dedicated ICSP connections on 12, 13 and 33, which allows you to use PortB.6 and PortB.7 pins for whatever you want. I could workaround that by using an input or output that's high impedance during programming so it's a minor issue for me.

The requirements I need are SPI, CAN, USB and one USART that doesn't use any of the SPI pins.

Right now I'm using the 18F4550. I have an MCP4912 and an MCP2515 connected to it. I'm also using the USB function and I need to use the RN-171.

There's no easy answer unless I move to a PIC32. It looks like there would be a huge learning curve but it would enable me to remove the MCP2515 and possibly the MCP2551 but I wasn't able to confirm that.

If the RN-171 only had SPI all of this thinking wouldn't be needed.......

[Christopher4187]

I had another thought. The SPI doesn't use the TX portion of the USART. If I was using the RN-171 as a transmit only device, it would work fine. When the MCP2515 or MCP4912 aren't being used, the RX portion of the USART is in high impedance mode. This simply means that I only have to figure out what to do with the RX pin. A reed relay should work, no?

[HenrikOlsson]

Hi Christopher,
Oh, the USART and MSSP module share the same pin on the 4550, that kind of sucks.
Honestly, I'd really look into using another device - but that's me.

/Henrik.

[Christopher4187]

I've been thinking about this. What about if I bought some 16F720's and used them to transfer data from the RN-171 to the 18F4550? How difficult of a task would this be?

[HenrikOlsson]

Hi,
Like RN-171<->USART-(16F729)-SPI 18F4550 you mean?
If you think it'll be easier than changing the PIC then fine. You may need to buffer the data in the 16F729 if you're in the middle of a SPI transfer with another device. What are you using the USB for? Perhaps you could you use a PIC with a MSSP module (SPI), built in CAN and 2 USARTS. Use one USART for the RN-171 and the other for FTDI USB chip or simmilar? (PIC18F45K80 is an example). Honestly, I don't know enough about your project so the only thing I can do is throw ideas up in the air and at this point I'm running out of them.

/Henrik.