RS-232
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What are the RS-232 and Transistor-Transistor-Logic (TTL) voltage level?
| Voltage | RS-232 | TTL |
|---|---|---|
| 0 | [+3V;+25V] | 0V |
| 1 | [-3V ;-25V] | Vcc (usually 3.3V or 5V) |
What is DCE and DTE?
DCE stands for Device Communications Equipment.
DTE stands for Device Terminal Equipment.
| Signal | DCE | DTE |
|---|---|---|
| RX | out | in |
| TX | in | out |
| CTS | out | in |
| RTS | in | out |
On the NXP i.MX6 the convention is a little different:
| Signal | i.MX6 DCE | i.MX6 DTE |
|---|---|---|
| RX | in | out |
| TX | out | in |
| CTS | out | in |
| RTS | in | out |
Bluetooth module, modems and GPS are generally DTE while computer are DCE.
Resources
| Pin-out | http://www.db9-pinout.com/db9-pinout/db9-pinout.gif |
