The other 2 dollar cheap ebay mp3 players. Worked out of the box, even the battery was not empty.
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Here we see a diffrent chip, GPD2086C found the datasheet online (google),
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in Chinese, but application diagrams are clear.
PCB front:
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Outside:
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No LCD, plays right away... Also with a 16 GB micro SDcard, site states 8 GB. Same charging circuit for lipo, 6.8 Ohm in series with si diode from USB power +.
On a sunny day (Tue, 24 Feb 2015 07:35:36 -0800 (PST)) it happened Klaus Kragelund wrote in :
I do not know, but it sounds great :-) I will have to modify these too for a MCP73831T charger chp. It is a give-away, but I could not give it with the current circuit.
I need a few of these for folks that can't see well. I want them to be able to be turned on and off by applying 5 volts to the USB connector and that it should start playing the same file where it left off.
On a sunny day (Tue, 24 Feb 2015 10:02:04 -0800 (PST)) it happened snipped-for-privacy@yahoo.com wrote in :
Hi Mark, please note that it has no internal memory, so you need a micro-SDcard, Yes, if you play it, and then switch it off (it has an on/off switch), then it is at the start of same song where you left.
There is a red LED flashing about once per second if it sees a card and plays. If it sees no card, or in pause mode, then that LED burns constantly.
When I connect it to my PC, then it must be in the ON mode (slide switch, visual impaired people should easily feel its position), dmesg (Linux) shows:
366518.943036] usb 5-2: new full speed USB device using ohci_hcd and address 29 [366519.112875] usb 5-2: New USB device found, idVendor=1b3f, idProduct=30fc [366519.112878] usb 5-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [366519.112881] usb 5-2: Product: USBDEVICE [366519.112882] usb 5-2: Manufacturer: GENERALPLUS [366519.120471] scsi50 : usb-storage 5-2:1.0 [366520.130747] scsi 50:0:0:0: Direct-Access Generalp lus SDC READER V 1.1 PQ: 0 ANSI: 2 [366520.130916] sd 50:0:0:0: Attached scsi generic sg3 type 0 [366520.140748] sd 50:0:0:0: [sdc] 30881792 512-byte logical blocks: (15.8 GB/14.7 GiB) [366520.150751] sd 50:0:0:0: [sdc] Write Protect is off [366520.150754] sd 50:0:0:0: [sdc] Mode Sense: 03 00 00 00 [366520.150756] sd 50:0:0:0: [sdc] Assuming drive cache: write through [366520.184745] sd 50:0:0:0: [sdc] Assuming drive cache: write through [366520.194765] sdc: sdc1 [366520.214741] sd 50:0:0:0: [sdc] Assuming drive cache: write through [366520.214746] sd 50:0:0:0: [sdc] Attached SCSI removable disk
This is with a 16 GB SDcard, it does recognize 16 GB, as opposed to what the web site says that it only works up to 8 GB cards I can mount the card and read or write it. When connected this way the red LED burns constantly, but flashes very fast when data is transfered.
Anyways, that way you can use it as card reader!
If you pauze it in the middle of a song, and then switch it off, then when switched on again it starts at the beginning of that song. Hope this helps.
PS when connected to the PC USB it cannot play, as it is then a card reader. That is for charging or putting songs on the card only. You could modify it, remove the battery, add a some low dropout 3.8 V stabilizer I guess. And put the songs on the card with some other device.
I don't know how they do it either. But - to digress a bit from your topic - we get things like that a lot here in this isolated corner of eastern India, sandwiched between Bangladesh and Burma. They are mostly brought in by smugglers via Burma.
An example: A gas cigarrette lighter with a focussed white LED complete with a switch and three button cells for INR5 (US$0.08) each or 3 for $0.16. It comes with a refilling valve but no one bothers. Bought separately, the button cells cost $0.30 or more
Place a switch circuit in the USB line that allows you to "remove" it.
There are hubs with switches and enable indicator LEDs all over the market.
One could run linux on the PC, and not have to worry about whether the idiot OS has a file open on the device or not.
Then, you can install a circuit to control the USB "switch" which the Linux OS would also control.
Feed the Audio out into your amp, and use a remote session or a direct session to control the USB switch for card loading and 'removal'. When the switch is off, you would then use the player. You could also place a PC controlled switch onto the power feed for it.
Buy a bit more expensive "player" and you could even get digital output.
OK, but that's not what he asked. I have the same question. Can you turn it on and off by applying power to USB. Not the internal switch, the application of USB power. I don't even care where it starts. If it just starts playing somewhere and continues to loop forever, I'm a happy camper.
EVERY mp3 player I've tried has no ability to PLAY AND Power from USB. Doesn't seem to matter if you break the communication pair. Merely applying power puts it into data transfer mode. I had to build a AAA battery eliminator to make it work, but that doesn't solve the issue of starting play be applying power. Soft buttons make that a problem, but if your player has a hard button, it may solve that.
Cellphones used as dedicated MP3 players seem to be able to charge and play at the same time.
I'm sure that someuno will offer a counterexample...
I am applying 5 volts only to the USB, no USB data. i.e. from a USB chargi ng wall wart.
I bought two oof these at diffeent times on ebay. THe first one worked as I need. I plug the USB wall wart into a switched outlet and connect the de vice to the wall wart. And powered speakers to the switched outlet. All that is needed to play music, is to switch on the wall outlet. The speaker s power on and the MP3 player gets 5 volts via the USB connector and powers on AND STARTS PLAYING. No need to press anything on the player. In fact the on -off switch is off. This is exactly what I need.
Unfortuntaly I bought the seonc on expecting the same behaivor and it does not start automatically. That is why I ask.
The player is such low power, I could just leave it on forever connected to a 5 volt supply and use the switched outlet to turn the speakers on and of f. The music will simply repeat at random.
On a sunny day (Tue, 24 Feb 2015 13:42:04 -0800) it happened mike wrote in :
Well, that is what happens here, and covers EXACTLY what the asked.
Read what I wrote.
Else f*cking buy on.
PS, I found that SOMETIMES when plugged into the USB with the power switch on the player set to OFF, it starts playing. Other times it just goes into card reader mode.
This seems to be related to charge in caps, that is why I had to remove the cap in the other player's mod. IF YOU BOTHER TO STUDY THE F*CKING DATA SHEET OF THE CHIP then you will find that the USB pins are likely pulled up by internal pullups, with very low current, it all depends how you plug it in, if it sees power or data first etc.
It would be VERY SIMPLE IF YOU HAD READ THE DATASHEET to cut the data pins or lift those from the peeseebee to always enter player mode.
PS I found that with a GOOD USB cable it goes into PC data mode, sometimes with the BAD USB cables (the very thin ones that come with it), it starts to play (switch to off position). So that may well solve the mystery for some other lurkers.
The GOOD USB cable is the once that came with my Canon camera. I have put the other cables away.
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