Digital Radio

[EN0]

Hi,

I'm in the process of designing my own radio using the Si4734. This thread will serve as a resource of my progress in the design (which will undoubtedly be slow!) as well as a reference for questions I have.

Question 1:

My goal is to have a tuning knob to adjust the frequency or whatever settings I have displayed on my LCD. Since I am completely new at this type of thing, what approach should I use? Would I use a digital encoder? Are there IC's available to do this?

Thanks,

Austin

 

[EN0]

Hello,

I found this online, and it seems like it would work:

http://www.austriamicrosystems.com/Products/Magnetic-Encoders/Rotary-Encoders/AS5030

The IC determines rotation by sensing the rotation of magnetic fields. Hopefully if I put another magnet close by it will not affect the accuracy of the sensor!

My goal is to have the dial turn without any limitations like a potentiometer normally would have; almost like the tuning dial on your car radio. I will continue to research more on reasonable ICs, and let me know if you guys find anything.

Austin

 

[ronsimpson]

ENO,

I did a project with the Si4734-(special version). I found the little square package to be hell to work with! I did find a way to solder them down.

I am using a thing that looks like a pot. Has a shaft encoder function. Optional 64 ticks per turn. Very simple.

What micro will you use?

 

[EN0]

Hi Ron,

I ordered the ICs and they are very small indeed! Fortunately at my job I have very fine soldering tips, so I will probably use them in addition to a pre-made PCB.

I would be interested in seeing pictures of your design if you have them! Also, do you have the datasheet to that shaft encoder you used?

I will probably be using a PIC24F or PIC32F series µC, which will be new for me.

 

[Gobbledok]

Hi EN0, look online for rotary encoders. You can buy cheap mechanical ones for a couple of bucks, or expensive optical ones.

 

[ronsimpson]

Search Digikey for Panasonic EVE-GA (EVE-GA1F1724B) for the rotary encoder.
For the Si Labs part do not use the standard footprint on the PCB. The entire pad (and pin) are under the part and there is no where to solder to. Make the PCB pad longer and have it stick out from the part.
This part works well with a LCD and small micro or even an PIC18. Why do you need a PIC24 or PIC32.
Is this a work or home project?

 

[EN0]

Hi,

Gobbledok, I'll be sure to search for that term. I want to make this a very nice project and so an optical encoder might be a good choice. Fortunately I have a summer job!

Ron, thanks for the encoder recommendation. I will examine the datasheet for further information. It's a good thing you've worked with these particular radio ICs before, because I might have made the PCB pads and lines shorter than I could have managed with. At my work I've had to work with some miniscule components (QFN packages even), so hopefully I will be able to solder with this one (time will tell).

I can use the 18F series but I want to get into 16-bit PICs and I might need more than a couple I²C or SPI serial interfaces. I am also working with a color LCD, so a more powerful PIC might be necessary? This is a home project that I came up with because I don't have a good radio. I have some hand-me-down radios that even use the flip-slides to show the time and the audio performance is very noisy.

Ron, do you have any pictures of your design that I can view or is it confidential?


I read more about the Si4735 and it has some very nifty features! I'm composing a list of all the complete project features I would like to include:

• Digital Tuning (Keypad or Rotary Encoder)
• Station ID & Song Name
• Memory Channels (Programmed through user in E²PROM of PIC)
• Play or record songs through USB flash drive
• Time (displayed on top of color LCD)

If any of you think of others that might be cool to add, let me know!

 

[EN0]

Alright, what I should probably do first is get a color LCD working. Does anyone know of a good website to find nice color LCDs that aren't extremely expensive?

I was thinking of the design looking similar to this:

I will, of course, have varying colors. But you get the idea.

Austin

 

[Gobbledok]

Hi EN0,

For my project I used **broken link removed**.

It is a 2.4" TFT with built-in touch controller and SD card slot. I'm using it with a PIC32MX but it is pretty easy to use, there are code examples on the eBay page.

One more idea to be implemented in your code if you have enough resources and speed, you could perform real-time FFT on the audio signal to display a spectrum analyzer on the screen like this (but in color and better).

Maybe it's overkill, but I would probably suggest that you go with the PIC32 yourself, especially if you plan on playing back MP3's from SD, etc. I think you will run out of RAM with any other PICs. The extra speed as well as DMA and PMP will help with the LCD also. PIC32's are fairly easy to learn if you have had experience with other PIC's.

If you end up using the PIC32 and ILI9325 LCD screen, let me know and I can help you with the screen.

 

[EN0]

Hi Gobbledok,

I appreciate the LCD information, it looks like an excellent LCD to use. My only question is if the source is reliable; have you purchased from that link yourself?

I think I will use PIC32's for this project, and as you mentioned, previous experience with other PICs should make it easier for me to learn about them (I've worked with the 18F series). I made a thread just for them, see this link on ETO.

 

[Gobbledok]

Yep I bought my LCD from that same seller

 

[EN0]

Perfect! I just thought I better make sure.

I will order two of them.

 

[mvs sarma]

hi ENO,
perhaps you might have already seen the design by Burkhard Kainka, in elektor at link below.
**broken link removed**
all the best in your attempt.

 

[ronsimpson]

I want a scan for new station function that is not like my car radio. It looks for the next station that is above some signal level that is not settable.
I want to scan through all channels then display a graph showing the signal strength on every channel. Then let me pick. This is good on short/long wave where activity may only happen 2 or 3 times an hour. As small as they are....I could have two Si radio chips, listen to one and the other could scan all day long.

ED0....if you were from this earth maybe we could work together. I usually get 5 to 10 PCBs at a time and maybe we could share in the cost.

What did I make? I can't say. That IC does many different jobs. If you look at Si you will see that same silicon under many different part numbers. It is not always used as a radio.

 

[EN0]

hi ENO,
perhaps you might have already seen the design by Burkhard Kainka, in elektor at link below.
**broken link removed**
all the best in your attempt.

Thanks mvs sarma, that looks interesting.

I want a scan for new station function that is not like my car radio. It looks for the next station that is above some signal level that is not settable.
I want to scan through all channels then display a graph showing the signal strength on every channel. Then let me pick. This is good on short/long wave where activity may only happen 2 or 3 times an hour. As small as they are....I could have two Si radio chips, listen to one and the other could scan all day long.

ED0....if you were from this earth maybe we could work together. I usually get 5 to 10 PCBs at a time and maybe we could share in the cost.

What did I make? I can't say. That IC does many different jobs. If you look at Si you will see that same silicon under many different part numbers. It is not always used as a radio.

Hi Ron,

If you look at my profile, it indicates that I am not from this Earth.

Now that you mention it, the Si4735 does have a signal strength feature using the command "FM_RSQ_STATUS". I will have to add that feature on the LCD display as well.

 

[EN0]

Menu Configuration

Hello,

I composed an outline of the menu I will have. It is still a tentative list, since I will most likely think of features I'd like to add in the future.

OPTIONS:
• Mute
• Receive Signal Quality (RSQ) of current channel

MENU:
• Receiver Settings
• Favorite Stations
• Time/Date
Note: Menu is initiated by pressing the center button (B in the example diagram).

RECEIVER SETTINGS:
• Operating Mode
• Complex Characteristics
• Tuning
• Reset

OPERATING MODE:
• Audio Output (Analog/Digital)
• FM Receive
• AM/SW/LW Receive
• Reference Clock

COMPLEX CHARACTERISTICS:
• Automatic Gain Control (AGC) for adjustment of internal LNA.
• AM Filtering – Seven selectable channels
• Channel Step Size (starting from 1 kHz)
• De-Emphasis/Pre-Emphasis
• AVC Gain Control
• RDS Configuration
• Antenna Configuration (Internal/External)
• Mute Settings

TUNING:
> FM
> AM/SW/LW

• Frequency Step Value
• Top/Bottom Band Seek Frequencies
• SNR Threshold
• RSSI Threshold

If you guys think of anything else, let me know.

 

[EN0]

Menu Configurations

Hello,

Since I couldn't edit the other menu configurations (it won't let me go into advanced for some peculiar reason) I am posting the latest revision.

OPTIONS:
•	Mute
•	Receive Signal Quality (RSQ) of current channel

FAVORITES:
•	A quick directory to your list of favorite channels.

MENU:
•	Receiver Settings
•	Favorite Stations
•	Time/Date
•	Information

Note: Menu is initiated by pressing the center button (B in the example diagram).

	RECEIVER SETTINGS:
	•	Operating Mode
	•	Complex Characteristics
	•	Tuning
	•	Reset

	OPERATING MODE:
	•	Audio Output (Analog/Digital)
	•	FM Receive
	•	AM/SW/LW Receive
	•	Reference Clock

	COMPLEX CHARACTERISTICS:
	•	Automatic Gain Control (AGC) for adjustment of the internal LNA.
	•	AM Filtering – Seven selectable channels
		o	6 kHz
		o	4 kHz
		o	3 kHz
		o	2.5 kHz
		o	2 kHz
		o	1.8 kHz
		o	1 kHz
		
	•	Channel Step Size (starting from 1 kHz)
	
	•	De-Emphasis/Pre-Emphasis
		o	FM
		o	AM/SW/LW
		
	•	AVC Gain Control
	
	•	RDS Configuration
		o	RDS Configuration Settings
		o	Receive RDS First In First Out (FIFO)
		o	RDS Source (Interrupt behavior)
		
	•	Antenna Configuration (Internal/External)
		o	Ferrite Bead
		o	External Antenna (e.g. a vertical wire antenna)
		
	•	Mute Settings
		o	FM
			•	Soft Mute Rate
			•	Soft Mute Maximum Attenuation
			•	Soft Mute SNR Threshold
		
		o	AM/SW/LW
			•	Soft Mute Rate
			•	Soft Mute Maximum Attenuation
			•	Soft Mute SNR Threshold
		
		o	RX Hard Mute
		
	•	Volume Settings
	o	AM/SW/LW
		•	Automatic Volume Control Maximum Gain

	TUNING:
	•	FM
		o	Frequency Step Value
		o	Top/Bottom Band Seek Frequencies
		o	SNR Threshold
		o	RSSI Threshold
		
	•	AM/SW/LW
		o	Frequency Step Value
		o	Top/Bottom Band Seek Frequencies
		o	SNR Threshold
		o	RSSI Threshold

	RESET:
	•	Reset Si4735 to default settings.
	•	Reset PIC to default settings.
	•	Reset Si4735 and PIC to default settings.



	FAVORITE STATIONS:
	•	Store your favorite channels in an external serial memory IC.


TIME/DATE:
•	Configure the current time of the PIC hardware real-time-clock (RTC)
•	Configure the current date of the PIC hardware real-time-clock (RTC)


INFORMATION:
•	Design information
	o	Si4735 Firmware revision
	o	PIC Firmware revision