July 29, 2000
Update: January 7, 2001
July 29, 2000
Update: January 7, 2001
This document introduces some points to build the kit version of the MP3 player.
Moreover, I think myself very happy as a project originator if assemble and put in the case and it is not an end but the improvement which is your own idea is added and open to the public. However, the one that it is still improved there doesn't seem that hardly be. Of course I hope someone to do modification of firmware at least as much as the replace SmartMedia to CF or MMC and to attach an LCD or any other display devices. When a memory card I/F is made a bus connection, I more think that it is attached as easily as USB or Ethernet controller. However, though the person who does it there is making an originaly pocket MP3 player without buying a kit :-)
But, on one side, though it makes up its mind and tries a kit, there is a person who can't be correct and who fails very much, and that most is a thing by the failure of soldering. Because the circuit diagram is very simple and no adjustment requirement, if a place to fail is said, though a circuit itself is as much as soldering. However, so though it fails in soldering and troublesome because it is the basis in the basis of the electronic handicraft :-)
Because it seems to say them, more than success rates 50% seem to be better than my expectations. (^^; (As a construction kit, it may a little difficult.)
And, any question on the kit version and any support related to the contents of this document aren't accepted at all. Because, to accomplish the project is your own work., I'm only introducing hints and tips on buiding the MP3 player.
First, a thick and short tip of the soldering iron is suitable for soldering on the PCB. (The tip of the soldering iron shown in right image is a standard tip of HAKKO MACH-I.) This isn't limited to solder QFP, and it is suitable for the whole of electronic handicraft. I don't recommend narrow and long tip for generic electronic handicraft because it tends to lack heat capacity. If it is limited to soldering of QFP, the tip cut like a tip of chisel is better.
The high-class article of 0.6-1.0dia of the solder is good. You had better avoid cheap solder. Its flow may poor or flux scatters.
In case of QFP, each side are usually soldered at a stretch because it takes time and a solder bridge cannot avoid when each one pin is soldered. A basic process is as the next.
Temporary solder : Put an IC to pad pattern correctly and solder each corner. Correctness is important, but taking care of solder bridge is not deeded.
Actual solder : Solder one side at a stretch with supplying much solder. Do it like to get pins wet with the solder which collected at the tip of soldering iron. Put up the circuit board with pin is moved downward, solder may not stick between the pins, and succeeds easily. It succeeds at a time without solder bridge if your soldering technic progressed.
Remove surplus solder : Wipe a tip of soldering iron, and remove solder bridge like in stroke pins with a tip of soldering iron.
Further, you must finish work while flux covers the surface of the solder and surface tension is kept though it is it. This can be said on the whole of soldering. To finish it quickly, pour away solder after pre-heats a junction point fully. This is one of the basic technics on soldering, but it is often kept.
If it has much trouble and flux evaporates and the surface tension of the solder is lost, you should supply a little new solder and start over. Further, in the soldering work of QFP, it is a knack to use a side of tip of soldering iron with lay down it, not at the tip of tip of soldering iron. It is using the nature of liquit which gets into the small gap.
When a bridge doesn't come off, it is one method to remove it with a solder wick, too. But, attention is necessary because the solder is removed too much and a pin may leave a pad.
The most ICs are not be damaged even if it heats it for a long time. Let's try without being impatient.
Progress isn't made in soldering if much soldering isn't handled because it is learned in the first place by the body. As for the way of remove a solder bridge, buy some junk circuit board and practiced by using that, it is good.
There are round patterns at the mount holes of the circuit board. This is for mounting the circuit board with screws as shown in the images. The circuit board can be fixed by this nut with a screw from one side. But, attention is necessary because it may exfoliate when a strong shock is given. You must cut the lead of parts short because the space of the solder side is restricted in the height of the nut.
There are four holes around DSP. As a matter of fact, it is because these holes were fitted to fix a battery holder and it was designed to mount a battery holder of two AAA battery. But, it is unnecessary on this MP3 player because it was changed to the operation of one cell of AA type battery and the battery could not be put on the circuit board.
A button can't be pushed any more because a button gets into the back when a circuit board is included into the case. At many commercial equipments, there are buttons of the case unity type, come to push a switch on the circuit board through that. A near one can be made though it is impossible that it is made by the injection of the plastic as well as them.
Left image shows the built button top. Cut the 5.0dia brass stick into the suitable length. Then, put a thin plate to one end to prevent to come off. It is good to try to be devoted to the appearance square stick make key top sculpture put, too.
The MP3 player kit doesn't contain the phone jack and the DC jack that fit to the PCB layout. And some substitution parts are being used besides this, the irresponsibility is Akizuki class :-)
The actual part number of the DC-jack is HEC3300-01-020 (Hoshiden), and the headphone jack is HSJ0887-01-510 (Hoshiden).
Some of the DSP (MAS3507D) might fail to start-up its built-in DC-DC converter. This problem appears as system supply voltage doesn't rise to 3V when PLAY button is pushed. This is a bug of the MAS3507D. To avoid it, DCEN pin needs any opration at the time of power up. The operation to the DCEN pin is to apply a sharp rise edge after the supply voltage is applied, it seems to be good to avoid that problem. Show an supplement circuit for that in the figure. Try when such a problem happens. It will become surely to start.
Try from add only R3 because it may be solved. The TC7S14 can be substituted with a 74HC14. Even one cell operation can use operating voltage of 74HC14 fully because it actually operates even less than 1V though it is from 2V. And, this problem happens by a F10 version of the present. It is said that it is amended with MAS3507D (G10 version) of the next version.
This is a report of extending an liquid crystal display as an example that a function was expanded. (shown in the image placed at head of this page.)
The right image shows an example circuit diagram that a general-purpose LCD module is connected to the MP3 player. The LCD module shares a data bus and some control lines of the memory card, and its strobe signal is controlled by PD7.(It is very easy. Isn't it?.)
However, when it operates easily, there is no interest :-) Therefore, though it is not a reason, it is that it is only connected simply and it doesn't operate.
Remodeling is a little necessary for the LCD module because it is as it is and it doesn't work in the supply voltage of 3V. (How to midify an LCD module is here.)
Well, could you connect it well? Then, let's try to program a firmware for LCD. What? Do you say where is the firmware? Write it by yourself that much! (.... it is a joke ^_^;)
Now, I open to the public the firmware neatly because it can't be helped even if it does something spiteful very much though it is about to want to say so. (The firmware for LCD is mpc094l.zip.)
The battery life will extended in two times if changed to two cell operation. Does anyone know such thing? :-) You will have to change the value of a part of the resisters if change number of batteries to operate. There is the following measure as a method except that the number of cells is changed.
This will the most effective. The output voltage of the DC-DC converter built into MAS3507D is 3.0V in default. But, an actually high voltage shows a tendency of coming out (3.1V or more). If the voltage is high according to measured by DVM, it can adjusted by edit set_dcdc routine found in mpc_iic.asm.
The 3.3V media can operate at 3.3+-0.3V according to the SmartMedia standard. Recently, they are called 3V media. When use a SmartMedia manufactured by Toshiba, it can operate under supply voltage of 3.3+-0.3V, so that the supply voltage cannot lower lower than 3.0V. At the SmartMedia manufactured by Samsung, it can operate at supply voltage of 2.7-3.6V. The manufacture ID is found in on-line message, Mfr=98 means Toshiba, and Mfr=EC means Samsung.
When replace the shottky diode with a ultra low drop out voutage diode, such as Toshiba 1FWJ43N, the effeciency of the DC-DC converter will be imploved and the battery life will be expanded. Though it is probably about ten minutes at most.
It is common sense that a cheap battery box should not be used for large current discharge of the NiCd batteries. As for this vessel as well, it can be said that it is the same. I explain easily it because there may be a person who doesn't know it, too.
There is a problem at the coil spring of the battery box. The resistance of the coil spring cannot be ignored because most coil spring is made of steel wire. The resistance is about 0.5 ohms for each one in case of a battery box for AA size. This means, when use it at load current of 1A, the voltage drops 0.5V x number of springs. Resistance value varies in the battery box. The white thing which showed it in the right image is 0.5 ohm. Another one was little resistance with the 0.2 ohm though it was a thin spring.
In case of this MP3 player, because it consumes about 200m A at input voltage of 1.0V, it decides to drop 0.1V at the spring. In other words, be deciding have 10% of the power spent in the spring. (It is very big.)
Let's throw such a battery box away, and replace it with the high-class article which used the plate spring of copper alloy. There is a way that a bypass does a spring with a copper wire as the right image to deal with it easily, too.
This MP3 player uses a SmartMedia in local format, such as bad block control, track management. When use a SmartMedia with this MP3 player, it gets cannot be recoginized again with any other equipments. This problem is due to destroying the format information of SmartMedia.
Full specifications aren't introduced to the public, yet. Therefore, it can't cope with it at present. If that is opened to the public, I will think that the function which has physical format with a SmartMedia standard again will be added. If you are interested in the SmartMedia standard, see the SSFDC forum.
This MP3 player can do the matter that CompactFlash is replace for this, too, easily though SmartMedia is used as storage device. The bottom figure shows an actual connection example. The CompactFlash must be defined in the 8bit I/O mode because only a lower byte of its data bus is connected. And, I don't open the firmware, because I have not written it yet :-)
