Si4735 Radio Chip and Prop?

Christof Eb.

Hi all,
has anyone played with the Si 4735 DSP Radio Chip? Elektor has written about it and it is interesting, I think. AM+FM+I2C+Digital out+RDS

I have a project idea in mind:

Have a radio
* Si4735, controlled by Prop
* battery powered
* 1*LM386 + Speaker·+ Line out
* PropBasic for low power due to low clock frequency
* Special feature: have a SD-Card and log news to SD-Card,·hear the last news, if you push a button.
* No special PCB, use Protoboard if possible.

Suggestions, Comments?
Christof

·

Leon

I wouldn't use the LM386, the sound quality is appalling. I haven't even used it for amateur radio applications for over 20 years. NXP makes some nice modern audio amp. chips.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Leon Heller
Amateur radio callsign: G1HSM

Christof Eb.

Thanks, Leon, for the comment.
Well, the LM386 is on my desk, cheap and low power.
I fear more, that there is noise coming from the Prop or LCD....
Christof

Leon

It is noisy, but there is lots of distortion as well. A nice chip like the Si4735 deserves something better.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Leon Heller
Amateur radio callsign: G1HSM

Christof Eb.

....to use the protoboard seems to be a very bad idea.

Power consumption 46mA with one cog running at 16*5Mhz. Can be cut down to 31mA with RCSlow or waitcnt.

OK, there is a bright green led. This bright???

The Propstick needs 17,2mA, can be cut down to 1,36mA. -Still a lot for batteries...

Christof

Phil Pilgrim (PhiPi)

It is a nice chip with a lot of interesting features, but it's obviously designed for entertainment, not communication. Two specs that indicate this: 1) no BFO, and 2) poor sensitivity (25-35uV @ 26dB SNR). In some cases it's possible to insert a carrier proximally to a receiver that lacks a BFO using a coil of wire driven with the intermediate frequency. But this chip seems to lack an analog IF section that could pick up such a signal. For the sensitivity issue, an external RF preamp might be an adequate solution.

-Phil