bout max232 & 877

[cyb3rfreak]

hi,

i would like to ask what type of input will the max232 accept.. is it analog or digital? either of the two, how do you set the 877 RC6/TX?

 

[dknguyen]

Well...it's digital since RS-232 is digital. But I have a feeling you meant to ask (or are confused) about something else, like the difference between an electrical analog signal and an electrical digital signal or something like that.

 

[cyb3rfreak]

something like that.. 'coz i want to send data from the pic to the cellular phone (i.e Nokia 3310). let say i want to send the word 'hello' from the pic and display it on the cellphone. some forums said that i need to convert it to hex codes.. is there a software that translate it into hex? btw, i was given this ckt on how to connect 877 and max232. my question, is it enough for this ckt to send data to the phone?
**broken link removed**

 

[Pommie]

That circuit shows just the RS232 part of the diagram. You will also need a crystal and associated capacitors to get the pic working.

Mike.

 

[cyb3rfreak]

That circuit shows just the RS232 part of the diagram. You will also need a crystal and associated capacitors to get the pic working.

Mike.

is MAX232 and RS232 the same? btw, sorry for missing the part... i already know about the crystal and cap.... ^_^

 

[Pommie]

A MAX232 is an RS232 level converter.

Mike.

 

[cyb3rfreak]

meaning, i need to connect the output of max232 to rs232 to obtain the desired output?

 

[be80be]

Take a look at this it should help you

 

[be80be]

Is this what your wanting to do use the lcd if so check this out
Nokia 3310 LCD Library

 

[arhi]

cyb3rfreak, if you just want to use lcd (as be80be suggested) you do not need rs232 at all as those old (3310, 5110, 6210..) displays are SPI and fairly easy to drive.

If you want to communicate between PIC and Nokia phone, then you do not need rs232 level shifter (that MAX chip) as both PIC and Nokia have same levels by default (0-5V) so no need to shift the levels to rs232 and then back to ttl.

With regards to communication between PIC and Nokia, you "cannot just send data and see it on the screen" as that would mean that your phone has some terminal emulation software, and most of them - do not, especially 3310

What you can do is talk to nokia 3310 using mbus protocol, google for it (few topics on this forum about it too) and make phone send sms, read sms from phone, manipulate data in phone etc... but this is "not easy". you cannot do that by just sending few codes to the serial port and the source code for this will not be few lines.

If you only want to use the PCD8544 based display like in nokia 3210, 3310, 3315, 3330, 3350, 3410, 5110, 5120, 5130, 5160, 6110, 6150, 6210, note that PCD8544 works on 3V and your PIC works on 5V so you need to do some level shifting. These display's are great, they do not consume too much power and are very easy to use + they do not use too many pins... I use them non-stop with msp430f2xx uC's

 

[be80be]

Your have to solder 4 wires to your phone or get you a F-Bus cable to send data serially. if you use the F-bus cable you could make Nigel Goodwin serial board and just plug it in. how to make it is here

 

[be80be]

arhi Thats what I was thinking you don't need the max just use pic's rc6 to tx and the rc7 for rx gnd hook it to the gnd pin2 on the phone and rx to rx on pin 3 of the phone and tx to tx pin4. But the code you send has to send a out a handshake just that part is a lot of code. But good luck it looks cool. I'll remember this when i want to get all the junk off my phone when i get a new 1. cyb3rfreak you can find a lot about it here it tell you about the hex you need to send to talk to the phone
Tutorial Microcontroller MCS-51 ATMEL ISP

 

[arhi]

be80be, yup, no need for max, but thing is you cannot use normal serial there, the darn thing need the pings on the f-bus or m-bus or .. forgot where .. so iirc you have to ping it on one wire every ~100ms and use rx/tx for communication ... if you use the data cable, there is already one pic16f84 or similar inside doing the pings so you can just use rx/tx, but then you have to use max to get the levels back to ttl.... if you bypass the cable, then you need to implement the pings...

I plaid with that some time ago, but gave up, gsm modules are "acquirable" and not too expensive, and when it comes to all those old nokia's, I just take the screen and batt (it if it usable) and throw them to garbage .. the spi screens are really good, I managed to make a small stock at home (some ~10pcs) but already "scared" what to do when they become unavailable

 

[be80be]

If you run out I have about 30 of them and a lot of regular lcd to

 

[dknguyen]

UART on a microcontroller is like RS-232 on a PC. They have the same communication protocal/language and can talk to each other. But UART on microcontroller is 3/5V digital signal and RS-232 on PC is +12V/-12V digital signal. MAX232 change voltage level so PC and microcontroller can talk to each other using UART/RS-232.

UART is a software standard for asynchronous serial communicaton and tell how digital message is organized. RS-232 (and RS-422, and RS-485) are hardware standard for UART and tell how voltage levels and electrical signals are sent and received.

Understand?

 

[be80be]

I no that but people are using the serial cable from the phone that you hook to your pc with a max 232 hooked to the pic not needed but done. pick 3/5volts and pc is 12 but not all of them lol now most don't even have a serial port or a floppy drive
Understand? fully

 

[be80be]

To send it hello the hex you send would be 68656c6c6f

 

[cyb3rfreak]

Is this what your wanting to do use the lcd if so check this out
Nokia 3310 LCD Library

thanks for the very useful guide Sir's! and for uploading the PDF i'll read it when i get home. partly yes.. but i need to use the cellphone itself (3310).. something like this... using F/M-Bus
**broken link removed**
**broken link removed**

 

[be80be]

That's it plug it in hook it to your computer open hyper terminal try that first then try it with the pic

 

[cyb3rfreak]

i would like to clarify about something, is this correct...
Max232 pin 11:RC6/TX, pin12:RC7/RX
Max232 pin 14:3310-RX, pin pin13: 3310-TX

**broken link removed**

To send it hello the hex you send would be 68656c6c6f

i'd like to use 'hello' as my example data to send it to the cellphone, but actually i only need to send NUMBERS and a COLON w/o space between characters and this data are acquired from different ports of 877 (e.g 33:153:58). 'coz someone told me that i need to pack it into 7bits, blah, blah... i dont really understand what he meant.