What to do?

[benryves]

Here's a datasheet for an externally controlled MP3 player (CF-based). :)

PICAXE chips are cheap and programmable in BASIC; they have a firmware built into them (which provides the BASIC interpreter) which means that you don't need an expensive programmer - the firmware supports serial IO, making the "programmer" a serial cable and a couple of resistors.

Edit: I already wrote some comms routines for the PICAXE to talk to the TI, too.

[rcfreak0]

You know that might just work! THANKS, but will the song info and all that just be displayed on the mp3 player, or can the calc display that on its screen also? I want the calc to control most of this.

(leaving comp class)

[benryves]

Hm, looking over it it does look rather crude (eg all files must be named in a specific manner - 001.mp3, 002.mp3, 003.mp3 &c) and I haven't seen a way to transmit song information.

[rcfreak0]

Oh,ok. so i guess that one prob. wont work.(but i dunno yet) NEXT my question still stands. Will those PIC chips from the links i posted earlier work to communicate from the calc to PIC to mp3 and back.
This is the mp3 player i want to use:(more than likely)
http://www.roguerobotics.com/products/electronics/ump3

EDIT:
Anyone reading this still? and anyone have any answers? :confused:

[benryves]

I daresay most PIC chips will, but they tend to require an expensive programmer and low-level programming (ASM). Education-targetted chips will typically come with built-in functions, a primitive BASIC dialect and no programmer requirement; the BASIC Stamp series are good but rather overpriced; the PICAXE series are roughly compatible and dirt cheap. (The PICAXE chips are just Microchip PICs with a special firmware pre-programmed on them). Hence my recommendation.

Your linked MP3 player has a serial interface; the Stamp/PICAXE chips have SEROUT and SERIN commands for serial comms. Would be very easy.

[rcfreak0]

soo, that robotic mp3 player will work with PICAXE chip? sweet. Thtas good, because i cant do ANY ASM programming .IF im right please let me know. Thanks for the info again.

EDIT:
Leaving comp class. ill be back on comp in about 3-3.5 hours.

[benryves]

Yep. The only issue I can think of is PICAXE availability in the USA (being a UK product); they are (apparently) distributed by these guys. You should really look at the individual datasheets to pick a model best for your needs.

The routines I posted for TI comms with a PICAXE only work with the 08 series, as you can switch pins between inputs and outputs at runtime with that series (the two data lines to the TI are bidirectional). However, they have very little space on them for a program, and the larger PICAXE chips have fixed input and output lines, meaning you'd have to hook up some supporting circuitry and use four pins (2 input, 2 output) rather than switching at runtime. Different chips have different capabilities.

If you have any questions, just ask!

Edit: Of course, your microcontroller between the MP3 player and the TI. The TI will need to handle IO too; Telnet 83+ (see ticalc.org) will be a useful debugging aid. As far as sending data in your own application goes, Omnicalc can send/receive bytes manually.

[rcfreak0]

wow, thanks for the information. Ill look into getting the PICAXE chip soon, and ill post wich one im looking at getting before i buy. looks like this project might acctually get underway :biggrin: . I will eventually have questions with the programming, as im really dumb in that area. I hope this all works. Imk gonna look at the PICAXE chips now, and ill posy back soon (hopefully). Thanks again,

--rcfreak0

EDIT:
would this PICAXE board work?
http://world-educational-services.net/cart...&products_id=10

And this PICAXE chip:
http://world-educational-services.net/cart...&products_id=28
or do i just need a chip and not a board? i fugure i need i board but i dunno, please help :confused:

EDIT(agian):
Im leaving comp classes, and school. I dunno when ill be on next since i just got grounded(i hate report cards). Ill try to get on when parents are not home, but i dunno when that will be. please keep posting answers and suggestions and whatever else you people find the need to post. I will keep working on this mod even if i dont have access to the comp.

[benryves]

The "model number" on PICAXE chips is made up by a number (08, 18, 2 and a letter. The number corresponds to the number of pins on the actual chip, the letter refers to any special features (eg the 08M is the 08 but with "music" capabilities - it can play simple tunes. More importantly, it has 256B EEPROM rather than 128B).

In short, the 28-pin development board will not be that useful with the 08-series PICAXE. However, that's not important; I use a small standard breadboard for development (photo).

If you look at the PICAXE datasheets you can see a circuit diagram for the programmer; it's a few resistors, a serial cable and a push button. I'm not sure where you can get hold of those components in the US, nor the tools to connect them together. Do you have much knowledge about electronics?

If the PICAXE is just to act as some sort of bridge between the two devices (the calculator and the serial MP3 player) the 08M might be big enough. However, space is really very limited on these small 8-pin chips, requiring you to code quite tightly.

I don't have any transistors so I haven't worked on a solution for devices without programmable input/output pins yet.

I worked on a little demo program; it silently transfers the real variable A from the connected calculator and writes it out (as ASCII text) over a serial connection. You can look at the source here and a screenshot of the output here.

[kermmartian]

Re: getting that parts. You can quickly get them (but get slightly ripped off) at RadioShack, or you can order from somewhere like http://www.mouser.com (but need to wait for their molasses-like shipping).

[rcfreak0]

Im not good with putting electronics together. thanks for the more info. ill be back on later to post more.

--rcfreak0

EDIT:
Im not good with electronics(as in putting them to geter) but my moms boyfreind is, and ill have his help. I cant really write code at all,so any help their is appreciated(greatly). Thank you benryves for all the help so far, its greatly appreciated. So to my understanding, this PICAXE chip will work. please let me know. I went out and bought a small solderless IC breadboard today, and it will work, i just need scematics on how to wire everything up in/to it once i get he PICAXE chip. Im going to order the PICAXE chip as soon as i know which one to get for sure.Thanks again for the help, and more is needed when it comes to the code and wiring.

--rcfreak0

[rcfreak0]

ATTENTION:

really no attention i just thought it would grab everyones attention,.
I finially ordered the PICAXE chip (O8M) on sunday. I dunno when it will come, but hopefully soon. Also how am i supposed to transfer data from my computer to the PICAXE? do i need to buy something else?, or can i use the breadboard and serial cable or something? i dunno at all. Please let me know. ill be on-and-off the computer, but ill be able to use it at school, not at home, so my replys might be time spaced. Let me know about anything else before i order the mp3 player and blow $100+ out the window(sorta). bye for now, let me know on anything.

--rcfreak0

[benryves]

The PICAXE's firmware will handle transferring the BASIC program to its internal memory; you'll just need to plug it into your computer. These devices are intended for educational use (so are easy to work with), and the programming software comes with all of the documentation you'll need.

One thing I didn't mention was that the PICAXE can also be programmed in a flowchart language (as well as BASIC) which might work better for your understanding. I haven't done much work with them, though, so can't comment on whether you can do everything you need to with them.

Here's one of the datasheets, giving you the pinouts and circuit diagrams for wiring up and programming these microcontrollers. All of the datasheets are bundled with the programming editor (a free download) anyway.

[rcfreak0]

Thanks. Any break i can get in coding will be a help. So ill be able to transfer data to the PICAXE using the breadboard, or do i need to buy something else? Im gonna look at the datasheet now.

EDIT:
This dadtasheet does help, thanks you lots. So from what i gather i can just wire a serial cable to the PICAXE controller to transfer data?

EDIT again:
leaving comp class be on later today. (3-3.5 hours)

EDIT agian:
im back for a bit. Also i now gather that i have to buy a prototyping board to tranfer data and that. am i right?

[benryves]

You'll just need to connect your PC to the PICAXE somehow.

Personally, I built a resuable board on a small piece of stripboard to help - it has a 3.5mm stereo jack socket to mate with the "official" PICAXE programming cable, a 5V regulator and diode for power, and the resistors and push-button required by the serial programmer. Out of the end come five wires; +5V, 0V, serial in, serial out and reset (reset isn't used by the PICAXE 08 series).

You could, however, just cut up an old serial cable and plug it into the breadboard, along with the other components required for programming. :)

(The resistors are required to protect the PICAXE; don't directly hook up the PICAXE to your serial port). Be careful!

You can leave the cable in-place when working on a project; you can even send data back to the computer to help with debugging. However, when finished, you'll need to tie the serial in pin low to stop it from floating.

This datasheet goes over interfacing circuits (ie, best practices for connecting common input and output devices) which might also be useful if you have limited experience with electronics.

My only real caveat here is how much data you will need to receive from the MP3 player; receiving large amounts of data at high speed is quite unreliable (missing bytes). I just looked at the spec sheet again and noticed that the lowest rated speed is 9600; the PICAXE line max out at 4800 and only then for the X parts (I'm sorry!) :\ The PICAXE-08M can send at 9600 by running at 8MHz (rather than the default 4MHz) but I'm not sure about receiving. I'll look into it tonight.

A possibility would be to have two PICAXE chips - the PICAXE-08M handling slow TI comms only, and a punchier, larger 18X (or similar) handling serial comms.

The protocol seems quite light, but the only way of working out if it'll work or not is to "try it and see", and when the parts are expensive that's not always a great position to be in.

[rcfreak0]

Thank you. Ill read that data sheet now while doing my homework. Im probbably just gonna buy a prototyping board just to be safe. If i have to buy another PICAXE chip let me know, ill order it ASAP. I have an 08M coming and it wont be hard to order more. well all the PICAXE has to recieve is song information, length, artist, and to control the volume and song selection. ALSO on the calc side of things, is it going to be a app or a program? which would be easier? Ill try and order a prototyping board tonight, so if theirs anything else you can think of quick before i leave comp class that i should order tonight, please let me know. Thanks again.

--rcfreak0

EDIT:
Im leaving comp class in 8 minutes.

[benryves]

The questionable issue is whether the PICAXE is fast enough to keep up with the data being sent from the MP3 player, or whether it would drop or scramble the incoming data. The only way to verify this is, sadly, experimentation. ;)

I'll report back any further thoughts.

[rcfreak0]

Oh,ok. Well ill still order the mp3 player, just not for a little bit. (i need more money!) Ill keep looking into this too, thanks for all the help so-far!

--rcfreak0

EDIT:
leaving comp class. Ill try and get on tonight, otherwise tomorrow in school ill be back on.

--rcfreak0

[benryves]

It might be possible, it might not.
My preferred way to do it would be to have two PICAXE chips; the 08M and an 18X (or similar).

The 08M, running at 8MHz, could perform comms with the TI calculator and output to the MP3 player. It would have to poll the pins the TI calculator is connected to and, if either goes low, it could receive a byte from the TI and use SerTxd to output it at 9600 baud to the MP3 player.
The 18X would handle serial input. It would have to buffer the data sent to it by the MP3 player, until it knew it was "safe" (according to the MP3 player documentation; receive bytes until you get the command prompt '>' sent back to you). At this point it would wait until the 08M is "ready" (the 08M could set a pin high when it was busy) before sending it (slowly) the data received from the MP3 player so it can relay it back to the TI.

It will ONLY work if the 18X can keep up with the data sent to it by the MP3 player; this very much depends how much of pause there is between bytes sent over.

The MP3 player could be played with *only* an 08M, but you would not be able to read back any information from the device (such as directory listings so you can find out which file to play in the first place!)

I can't see a way to get track titles back from the MP3 player; you can get directory listings (ie, the file name) though.

[rcfreak0]

ok, so what if i just ran the whole mp3 player with 18X chip? I know i already have an 08M and a proto board for the 08M at home, but wich would work better using 2 PICAXE chips or just one. I might as well go with using two beacuse i already have stuff for the 08M. Aslo is their a way to overclock the 08m and make it run faster? i dought it but it's worth asking.

EDIT:
Im leaving comp class in 3 mins. ill be back on on about 3-3.5 hours.

--rcfreak0