cbergeron

Do you guys already have code started for the 18f ? If not, I might be able to help.

From what I've read, the underlying bus is i2c correct?

Kind regards,
CB

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rando

PM Sent (again).

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Dexter

I am not really familiar with the 18 family of chips, but what prevents you from using something like a 16F876. It has built in UART also, slap a max232 on it and its uber easy to get serial going. cant you use one of those FTDI rs232 to usb chips for usb? i also got I2C code working on the same chip, via the UART, IIRC (its been awhile...)

Edit: oh yeah, i have an extra 18F chip, i think. I got it in a pack of samples, but im pretty sure my programmer cannot do 18F chips. Let me know if one of you guys want it.

Chris31

Use the I2C-RS232 code example from here.

http://www.emicros.com/pic1.htm

From the RS232 use the code to convert it to USB as found on the microchip 18F/16F series USB PIC app notes. With code alteration to suit the targeted MCU of course.

The PIC will then appear as an emulated comport via USB. or just write a straight I2C-USB code. All best done in assembly, C or BASIC are ghey in PIC

Go for the 16F because they are much cheaper.

Edit 16C I meant

Chris31

I simply cant see the point in having a serial support when the USB is already there. Unless the cost of MAX232, 5 caps, 1 DB9 connector and space needed for those components are considered ok. Which I dont think so.

Just slap in a 16C745 USB PIC and a software emulating the I2C on 2 of the pins. A much much cheaper solution.


Here

1 x PIC 16C745
1 x XTAL
3 x capacitor
2 x resistor
1 x USB port

Dexter

yea bit bang the I2C

rando

True but there aren't any 16F parts with USB hardware, only OTP. So we could have saved a few bucks on a cheaper 16F but then add it right back for the FTDI and supporting chips, larger layout, etc. The 18F looked to be a cleaner and ultimately cheaper solution. It's a fairly powerful beast and since it's flashable, it leaves open the possibilitiy of extending the radio to possibly do other things of interest to the community (relay control, temperature sensing, dead reckoning, ...).

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rando

Right, and if you're going to bit bang, you might as well just ditch the PIC all together. You can bit bang directly from the PC serial (+ level converter) or parallel port.

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Dexter

Sorry
Gotcha now. I thought the cost of the 18 family was really high compared to a 16 and some extra components but i havent really checked it out lately. sorry again. If you want my 18 chip you can have it, i have no use for it.

rando

The 18F2455 is listed at ~$9/ea at Digikey for single unit quantities but drops to $5/ea for purchsees of 25. That's why we're thinking about doing kits to keep the cost down.

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rando

No apologies needed ... we're open to discussing ideas.

The 18F2455 is listed at ~$9/ea at Digikey for single unit quantities but drop quickly to $5/ea for purchsees of 25. That's why we're thinking about doing kits to keep the cost down.

Hold on to the 18F. You might be able to use it to assemble one of these boards.

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racemier

Hi,

I'm back from a week of snowboarding and ready to kick ... again.

First of all some info about the features of the prototype:

AM/FM car tuner module
RDS/RBDS
USB controlled
Serial output (without MAX232), example for use with small LCD with RDS info
I²C output, to connect other I²C devices and control them through USB.
Phone input (with activation input to switch the sound processor)
AUX input
4 channel output (LF-RF, LR-RR)
Antenna/amplifier output

The unit uses a car tuner module, RDS-and sound processor. All this is controlled by I²C and through the PIC by USB.

I had some trouble with the prototype PCB (holes with incorrect size etc) so I adapted the PCB layout and decided to have 2 prototype PCB's made by a company nearby (had no time myself due to holiday). They're ready on friday (02/04) and will be assembled in the weekend. When they are working one will be send over to Seth for lab testing and one I keep here for testing.
If they fulfill the expectations I will most probably convert the layout to one with normal components for those who are not that big of a fan of SMT soldering (it's quite fun if I say it myself ).

Rogier

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jbors

Just wanted to have some comments on design but cannot read schematics due to the small size of it. Also interesting in something similar( but simpler ) with fully digital sound.

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Zac

How would it be simpler with digital in? There's quite a bit more coding to get digital in.

rando

@jbors: See the FAQ. Digital audio is within reach of the current solution -- You'd have to roll your own firmware to do the A/D sampling using either the on board converters on the 18F or with extra hardware. So too your firmware and OS USB drivers will need to deal with the audio stream.

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