[From QnA]WIZ812MJ interface(rs232, SPI...)


Hi ,I want to plug my wiz812 on a rs 232 db9 pins 2,3,5,where i’m going to connect them on wiz812mj board,I did circuit "Remote control via internet "I tried to use an Wiz110sr and not good circuit ,I changed to Wiz812mj it get one stage less ,I suppose than I can connect directly pins 2,3 of db9 to Wiz5100 ,How can I do that.
Many tks


Hello Sylvio,
Thank you for your interest to WIZnet and our products.
The you cannot directly connect RS232 pins to W5100 because a large voltage level difference. W5100 has 0 ~ 3.3V but RS232 pin has -15 ~ +15V.
So you should use RS232 tranceiver chip such as SP3232EBEY between RS232 and W5100.


Hi,I red other answer an flushed last message but I 'm back to same first question ,witch Wiz812mj pins are the connection with max233’s I say max233 side but not Wiz812mj side and also it is programed yet (Wiz812mj)or we have to programm it ,where we can find it and tool to doing it???.


Hello Sylvio,
Course the WIZ812MJ has no RS232 interface.
You have to use a MCU to use RS232 communication between RS232 tranceiver and WIZ812MJ.
Generally, a MCU has RS232 interface for serial communication and address/data line to interfacing with WIZ812MJ.
About second question, you don’t need to program WIZ812MJ because there is no memory for programing. Just use it for your application.
Your application code should be programed to memory of MCU.


Hi,many tks for your infos I beleive I did a good choice ,may be I did bad explanation about like I wanted to say,On wiz812mj there is two raw of pins J1 and J2 ,with definition at each pin.MCU side no problems all is clear but module side no I am sure I will use 3.3 volts+ground and 2 others pins to couple module to MAX 233 .What I needing is which pins are input and output to RS233.
I’m trying to explain better than I can english is not my first language about me this clear because I write in my words but It is difficult for an other to understand my asking.


Hello Sylvio,
You don’t need to connect between WIZ812MJ and RS232 tranceiver ship.
Because the RS232 chip is connected with a MCU.
Let me explain about the interfacing structure below.
RS232 connector <=> RS232 tranceiver <=> MCU <=> WIZ812MJ <=> MACJACK
So the interfacing between the RS232 tranceiver and a MCU depends on your MCU.


Tks for reply,may be I forgetten some thing,I get a projet a board with a Atmel 89s52 like MCU ,this board catch infos like temperature and with the module I will be able read them by lan connection,Perdonne to boder you with this question I thought it was possible to use this module to complete projet’s.


Hello Sylvio,
Glad to hear that!!
I hope your successful demonstration.