2.4 ghz WiFi ID

[Christopher4187]

I've given this some thought. I think I'm going to get rid of the RF devices and just use the MCP2515 on the SPI (I want to keep this because I can add other SPI devices with ease) so that leaves where to put the RN-171. Isn't the MSSP on the same pins as the SPI? If so, what about using the SC16IS750 for the RN-171? I've never used it but it looks like it should work. What do you think?

[HenrikOlsson]

Hi,
I think we're just talking above each other heads here.
Yes the MSSP module IS the module doing SPI so of course the MSSP-module uses the SPI pins on the PIC. But, again, if you're using SHIFTIN/SHIFTOUT to do your SPI communications then your are NOT using the MSSP module - even if you happen to have the MCP2515 connected to those pins.

If you're ditching the RF-module that frees up the USART to be used with RN-171 does it not?

The exeternal one you linked to has one advantage though and that's its internal 64 byte buffer giving you some flexibillity.

If you're still in a position where you can add external circuitry why not simply change the PIC to one with two USARTS (the 18F45J50 for example (there are plenty)) instead of messing with external ones? Or, again, use SERIN/SEROUT for one of the modules and the USART for the other.

/Henrik.

[Christopher4187]

Regarding the SPI, I'm using the SSPBUF to send and receive data. That's not shiftin/shiftout, is it?

I've thought about using another PIC but then I'd have to redesign. In addition, the 18F45J50 doesn't have dedicated ICSP pins. I'm not opposed to it but I've put a lot of work into this product. However, if I'm going to redesign, I might as well go for it all and use a PIC24, PIC32 or DSPIC33 because they have CAN, USB, SPI and USART. Does PBP even support them?

I feel like I've painted myself into a corner.

[HenrikOlsson]

Hi,

Regarding the SPI, I'm using the SSPBUF to send and receive data. That's not shiftin/shiftout, is it?

No it's not. If you're manually putting your bytes into the SSPBUF regisiter then you are using the MSSP module for SPI - great! Thanks for clearing that up!

I've thought about using another PIC but then I'd have to redesign. In addition, the 18F45J50 doesn't have dedicated ICSP pins.

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?

Does PBP even support them?

No it does not. PBP supports PIC10, 12, 16 and 18 series. Rumour has it that there'a version for PIC24 in the works but I have no idea if or when that'll be available.

There are several PIC18 series devices with CAN built in but unfortunately none of them have USB-support too. PIC18F66K80 for example have 2 USARTS, 1 MSSP module and 1 CAN-module.

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.

/Henrik.

[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.