Max3110e issues

[richb]

Max3110e issues-solved

I'm currently trying to just use the RS232 line drive in the MAX3110e with the USART of the PIC16f877a.

I've linked pins

25 (TX) to T1 IN
26 (RX) to R1 OUT

and

T1 OUT (Tx) to RS232 RXD (pin 2)

R1 IN (RX) to RS232 TXD (pin 3)

Vcc and ground are also connected.

When i connect this to a MAX232 everything works fine, but when i move it over to the MAX3110e nothing is coming in.

Any ideas guys.

Thanks

Rich

 

[eblc1388]

On the Max3110e, have you connected the /SHDN (pin 20) to +V (pin 21)?

 

[richb]

ok i tried that, and now i'm getting something on the terminal line. Unfortunately its all gibberish.

 

[ombrastein]

not sure if i read correctly what you have done, but in any case, make sure you also connect pin 5 in the rs232 plugg to ground in your circut.

Im asuming you alrdy did that tho...

What do you mean by giberish? weird ascii characters?

 

[richb]

Yep i had also connected pin 5 to ground.

It should print as a test

Hello
Hello
Hello

but this is what i get

HHHl
e
 áHee
Heo›
›llo
 "lHe›šÎHš
          œHH
HHlHo  HH²³ ¨‹ûŠþH
   HeeHoú
l
llHHlHH

Oh, tried several chips too, as i've seen this when you blow up a max232, but get same on each chip

 

[richb]

Issue Solved

I found that the MAX3110e worked fine when utiliseing a seperate power supply to power it.

I looked around and found that by adding caps to both of the PICS vdd lines, it seems to allow me to power the MAX3110e on the same supply as the pic.

This maybe a typical newbie thing, but I'm still learning