Telit Wireless Solutions GE863-QUAD Manuale Utente

 
 
 
 

 

 

 1vv0300715 Rev. 1 - 19/09/06  

  

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved 

 

page 26 of 79 

 

6.2 MODEM  SERIAL  PORT 2 (Python Debug) 

 
It is available on the following pins: 

 

25 

TX_TRACE 

TX Data  

CMOS 2.8V 

26 

RX_TRACE 

RX Data  

CMOS 2.8V 

 

6.3 RS232 level translation 

In order to interface the Telit GE863-QUAD/PY with a PC com port or a RS232 (EIA/TIA-232) 
application a level translator is required. This level translator must 
 

•  invert the electrical signal in both directions 

•  change the level from 0/3V to +15/-15V  

 
Actually, the RS232 UART 16450, 16550, 16650 & 16750 chipsets accept signals with lower levels on  
the RS232 side (EIA/TIA-562) , allowing for a lower voltage-multiplying ratio on the level translator. 
Note that the negative signal voltage must be less than 0V and hence some sort of level translation is 
always required.  
The simplest way to translate the levels and invert the signal is by using a single chip level translator. 
There are a multitude of them, differing in the number of driver and receiver and in the levels (be sure 
to get a true RS232 level translator not a RS485 or other standards). 
By convention the driver is the level translator from the 0-3V UART level to the RS232 level, while the 
receiver is the translator from RS232 level to 0-3V UART. 
 
In order to translate the whole set of control lines of the UART you will need: 

•  5 driver 

•  3 receiver