completed fm radio project
softcon
Posts: 217
Well, I have to thank Kevin of the technical support staff, and parallax again. After walking me through the complete installation of the fm radio module on the propeller quickstart board as mentioned in my previous thread, (definitely something I would not have been able to do with out Kevin's assistance since I can't see) my 9-year-old son is thrilled with his fm radio. It was built as a project for school (to get him into the gifted program) and I think it will do the trick nicely. We used the translucent blue case to hold his completed project. One of the end plates has a port slot that lines up perfectly with buttons 6-3 on the quickstart board, so we installed that at the front of the case, to keep the board as protected as possible. Initially we'd left the front open entirely to allow access to all the buttons, but this proved problematical because wires got pulled, and earphone cables were getting in the way. So, we used a plate with (what I'm assuming is a 25-pin port apature) on it, and this is the perfect fit for providing access to 4 buttons, which is all that's really required for the operation of the radio. By doing so though, it was necessary to modify the code to use the buttons in question. After only showing him how the button code worked, he was able to make the modifications himself, and we even added a default channel so it starts out on his favorite local station as soon as it's turned on, as well as adjusting the initial volume level. All of this with about 2 or 3 minutes of explanations of how the code worked. All the work was done by my son first, then I made the mods on another machine to match his since his computer won't talk to the propeller for some reason. I think it's a driver issue, but anyway, it works this way too. 
My son is very pleased with the results. We had to splice a radio shack 9-volt battery clip onto the parallax provided one because him and his friend broke the original one, and that part I didn't make him do, although it may have been a nice exercise in fixing things, but I didn't want to ruin the only power source we had. (definitely need to buy extra battery clips next time) We also added an extension cable, so that now there's a cable hanging out the back of the case which allows earphones or speakers to be plugged in without stressing the propeller board or the fm chip itself in the least. Unfortunately, radio shack had nothing shorter than a 6-foot extension cable, so most of the cable is coiled up behind the propeller board inside the case, but that actually helps to keep the cable tight, and prevents pulling and tugging when performing the actual plug/unplug operations. Also added was a battery clip to the back of the case, held in place by some sort of snapping clip (claims to be stronger than velcro) and the 9-volt battery slides in/out of this clip nicely for easy changing when the time comes. The only other thing that needed done was to tape the extension cable to the case to hold it still at the front of the case, so the wire doesn't fall down on top of the touch buttons and cause problems. So, the channel up/down and volume up/down are all accessible through the slot in the front of the case, and there's a perfect round hole all the way to the right that I hope (eventually) to put a on/off button into so he doesn't have to keep disconnecting the battery to turn off the device. He's having fun with his powerpoint prresentation explaining how he built it, and is very excited about buying more things from parallax so we can build more things. Again, I have to say thank you to parallax, and Kevin in particular for taking the time to work with me on this initial explanation. As you can tell I'm sure, my son (and me too) are very excited about his project, and I for one intend to build more projects for sure (talking thermostat for one) and I look forward to a long and fruitful experience with parallax products.
My son is very pleased with the results. We had to splice a radio shack 9-volt battery clip onto the parallax provided one because him and his friend broke the original one, and that part I didn't make him do, although it may have been a nice exercise in fixing things, but I didn't want to ruin the only power source we had. (definitely need to buy extra battery clips next time) We also added an extension cable, so that now there's a cable hanging out the back of the case which allows earphones or speakers to be plugged in without stressing the propeller board or the fm chip itself in the least. Unfortunately, radio shack had nothing shorter than a 6-foot extension cable, so most of the cable is coiled up behind the propeller board inside the case, but that actually helps to keep the cable tight, and prevents pulling and tugging when performing the actual plug/unplug operations. Also added was a battery clip to the back of the case, held in place by some sort of snapping clip (claims to be stronger than velcro) and the 9-volt battery slides in/out of this clip nicely for easy changing when the time comes. The only other thing that needed done was to tape the extension cable to the case to hold it still at the front of the case, so the wire doesn't fall down on top of the touch buttons and cause problems. So, the channel up/down and volume up/down are all accessible through the slot in the front of the case, and there's a perfect round hole all the way to the right that I hope (eventually) to put a on/off button into so he doesn't have to keep disconnecting the battery to turn off the device. He's having fun with his powerpoint prresentation explaining how he built it, and is very excited about buying more things from parallax so we can build more things. Again, I have to say thank you to parallax, and Kevin in particular for taking the time to work with me on this initial explanation. As you can tell I'm sure, my son (and me too) are very excited about his project, and I for one intend to build more projects for sure (talking thermostat for one) and I look forward to a long and fruitful experience with parallax products.
Comments
As a suggestion... Possibly the 9V battery could be replaced with a 4.5V or 6V battery (using 3 or 4 AA or AAA batteries). These could then be rechargables and also should last longer that the 9V battery. This of course depends on whether the 9V is actually required. Pololu www.pololu.com have nice battery enclosures with a power switch for about $1.50. You will need to fit the correct connector on the end of the cable though.
I bought a portable speaker for my laptop. It was designed for iPods etc. It came with a short stereo cable and a miniUSB to USB cable for recharging the internal battery. It cost ~$15 and is called iSpeaker. There are a number of similar products on eBay. It works really well.
Dittos also about the batteries. I like AA NiMH Energizer 2500mAh. 3 of them add up to 3.89V without a load hot off the charger, and since the propeller is such a glutton for punishment(read tough), would probably run most propellers just fine without any regulator all the way down to about 2.7V, which is a pretty dead NiMH. This simplifies things, but it not recommended for more than hobby projects.
Doug