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Forum Index : Microcontroller and PC projects : $3 MP3 player module...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9590 |
Hello everyone. 
As a follow-on from this thread about the Catalex $6 MP3 player, a different small and simple module was brought to my attention in that thread by melbnz. 
They are incredibly cheap at US$3 each, including postage. $3 MP3 player link They have a micro-SD card socket, headphone socket and USB socket all on-board. They also work as a card-reader which is a very nice bonus - plug it it with a card loaded in the socket, and the computer will see the card as a removable drive, making transferring files to the module a breeze. Normally with modules like this, you have to move your files with a card-reader, then put the card in the module, but this module takes care of all that for you too - pretty sexy for three bucks!
The module uses the GPD2806 MP3 decoder chip which is only a 16-pin SOIC which is quite amazing that it is not something in a denser pin-pitch package with more pins then that! But in that package, they get the MP3 decoder, the SD card handling, the button control and even provision for an external FM radio IC too - quite astounding, really, considering it's footprint, pin-count and cost of the module. The manual I have linked to above is in Chinese - you need to run it through Google Translate to make any real sense of it(unless you can read Chinese), but the diagrams and charts are still useful to have. The main page of the PDF reads as: 
Unfortunately, the control buttons are in some form of matrix, and not just directly grounded, so directly interfacing the buttons to a MM for control won't be possible without some kind of isolation, but I will have a think about that - even cheap reed relays would do the isolation nicely and when you only have five buttons.... I have not played anything on it yet, but I will hook it up to my amplifier later today. My main interest in this module, is as a player controlled by the MM. Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2932 |
I have used 4066's very successfully in several applications where I use a MM to 'control' a remote. In fact I have over used them on some occasions as some switches where 'grounded' (i.e. where I could have omitted a 4066 gate). There are many other ways to do this, but a 4066 is my choice  |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9590 |
Ahhh, yes, the good 'ole 4066 - did not think of him! 
I have several SOIC 4066's, so that looks like the way forward there - even cheaper then using reed relays, although, you can get ten SIL reed relays for US$6 on eBay... EDIT: These are what I am talking about. Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9590 |
Nice and easy to get working, but you have to make sure you REMOVE the USB power, or the unit won't play anything. Obviously once it is using the USB to act as a removable-disk host for the uSD card, it is in that mode for as long as the USB is connected, so you have to remove the USB connector, and put 3v3 on the little battery connections at the bottom of the board. USB file copy speed averages about 710kB per second, so not exactly fast on the data transfer, but the fact that such a cheap and small chip can do it at all along with being a MP3 player is still rather impressive IMHO. As soon as you power-up, the unit starts playback. I have not yet been able to get it to remember where it was in any playback, and resume once you turn off the power. I think the easiest way around that is simply to issue the PAUSE command when you "Power-off" the system with a power button, then when you power back up again, the MM can un-pause and playback will resume. Sound quality is fine, and I am now going to try with a few different songs and check it's skipping speed etc. EDIT: Songs play and pause fine(no missing bits when you un-pause), skip speed is about half-a-second in either next or previous directions, and maximum volume IS NOT set at power-up, so you can get more push from it by pressing the volume up button a few times. Songs play in a continuous loop. The player DOES NOT stop unless you stop it, so if you power up and leave it alone, it will go from song to song to song, and then loop and start playing them all again. Red LED blinks at approximately 1Hz while playing. Smoke makes things work. When the smoke gets out, it stops! |
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