Help me with RS232 in coin operated coffee machine

[t1000x]

coin opeated cafe

hello everyone, i saw a project from a website;www.weavefuture.com. I studied all the details, pictures, informations and already downloaded all the softwares needed from the site. I started to gather the materials to test the project, but its only a local parts I got. A PC, a coin selector HI-06cs, a timer circuit using ATMEL 89C51 which is really different from WEAVE FUTURE cos it doesnt have an RS232 connector terminal. I just assumed that pin 10 (RXD) and pin 11(TXD) of 89C51 were directly connected to pin2 and pin3 of RS232 terminal. So i got an old SERIAL MOUSE (RS232), cut its wire, and configure the color wirings according to its pin # connection. then i connect it to pin 10 and 11 of 89C51 in accordance to pin terminal of RS232. I followed the instruction in WEAVEFUTURE on how to install the software, but when i test my project, i was upset The software was not responding, but my timer counts. I assumed that my idea in this project was missing something like additional circuits or programs.
And now, im asking all of you goodhearted people to share me some info or tips that would might be helpful for me in accomplishing this project.

thank you very much and more power to EDABOARD!

 

[GrandAlf]

coin opeated cafe

You cannot directly connect TX-RX pins directly to a PC. It would be OK if you would just be sending data from chip to PC, but not the other way. RS232 output from a PC and terminal can swing to +- 12V, this will kill any MCU so connected. You must use a level translator chip, or do it with discrete components. Suggest a google for "rs232" will get you the info you need. Hope this helps.

 

[t1000x]

Re: coin opeated cafe

thanks for your help... im still searching and working for it and post update from time to time

 

[GrandAlf]

coin opeated cafe

Probably the easiest way to do this, is to use something like the Max232 chip, this has an onboard -+voltage generator and only requires the addition of a few capacitors to form a complete RS232 solution. Be aware however that you may have well blown the serial input on the chip you have now, if you have connected directly to pc. Good luck and keep on trying.

 

[t1000x]

Re: coin opeated cafe

yeah, youre right! i saw a circuit that could be an additional to my missing link and that uses a MAX232 ic by maxim. im also considering the use of usb-rs232 circuits. but im still keep on researching and studying for the best circuit, maybe after this i will post an image to show it here, so that everyone can give me the best advice in constructing this circuit. im really overwhelmed to your help

 

[t1000x]

Re: coin opeated cafe

i got a circuit that i want to try, its very simple but i will replace the parts cos of its availability. BC548=C1815, BC559=A1015. what do you think?

 

[t1000x]

Re: coin opeated cafe

the circuit i tried never works. im afraid that my port was already worn, so i try it into another pc, but still not working.... anyone can help me solving this?