Hi Massimo, =20 I hope you are doing well. About your problem, here are some comments. Fi= rst of all, I used 100nf ( .1) caps for the MAX232 charge pump in my appl= ications. So 1uf will work well at 19200. The 100nf caps will work much b= etter in applications with 115200bps for example. It offer many advantage= s in the slew rate transitions. The MAX 232 is a quite simple chip, and if you follow the data sheets, it= works very well. Then, you can check many things. First of all, the value you write in the= BAUDRATE register, and the cristal you use for your application. Then if you are using the Hiperterminal or minicom, hide the "local eco c= haracters" from your terminal. If you do so, you will hide the Enter, or = any other key you write to the terminal. Another interesting thing to check is the handshaking mode. Perhaps, it w= ill be useful to begin setting "No Handshaking" or disable the Handshakin= g mode. =20 I hope you solve your problem soon. =20 Kind Regards, =20 Mart=EDn. Instituto Argentino de Radioastronom=EDa. Peter Moreton wrote: I saw a similar problem when the PCB had been wired without +5v to the MAX232. The '232 sometimes worked, if data was being sent quickly. Someho= w, the MAX232 was generating a tiny voltage on the VCC pin. (I measured 1.5v= on VCC of the '232) I don't think your problem will be caused by having 1uf caps instead of 1= 0uf on the charge pumps. I use a MAX232CSE part with 1uf caps all the time. Obviously, it's best to use the correct part as specified in the datashee= t, but I don't think this particular part is critical for short RS232 runs. Peter Moreton -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf = Of Massimo Gaggero Sent: 27 October 2004 14:46 To: PIC List Subject: [PIC]: Another problem with RS232 - PIC16F873 Hi everybody, a thread has not been closed on RS232 that I am on beginning an other! I have a pic 16F873 that sends through its USART module (19200, 8N1) the = "M" & "G" characters (my initials). USART output is sent to a MAX232 but what I have on my terminal (Windows HyperTerminal) is only few "M" & "G" between many garbage, and I have to press continuously "enter" to see the output in the terminal (I have also tried minicom). Does anyone have an idea where is the problem? A thing that makes me suspicious is that the capacitors of the MAX 232 (a= ll except the 100 nF between Vdd & Vss) have the value of 1 uF (as wrote in = the datasheet for a plain Max232CP, not A). But in many schematics I have see= n capacitors of the value of 10 uF. May be this? Thank you, Massimo. -- ____ ____ ____ _ _ / ___)| __ \/ ___)/ /| | Massimo Gaggero (max@crs4.it) | (___ | /\___ \\__ | Net & System Management \____)|_|\_\(____/ |_| Phone: +39 070 9250 329 _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your members= hip options at http://mailman.mit.edu/mailman/listinfo/piclist _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist Correo Yahoo! - 6 MB, tecnolog=EDa antispam =A1gratis!=20 Suscribite ya http://correo.yahoo.com.ar/ _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist