| ??? 01/25/09 13:50 Read: times |
#161730 - Resistor is NOT an answer! Responding to: ???'s previous message |
Jecksons Ben said:
With resistor as voltage devider will ok... Unless you have some private insight not shared on the forum, you don't know what particular GSM module the OP is using, and you don't know what specific "89s51/8051" microcontroller he is actually using. Without that knowledge, you cannot possibly know what voltage levels the GSM module uses, nor the "89s51/8051". Therefore it is completely pointless to suggest any specific solution when the problem is unknown - there might not even be a problem, if the particular parts do happen to be compatible! But let's just say, for the sake of example, that it's a 1.8V GSM module, and a 5V MCU: A simple resistive divider will certainly convert the microcontroller's 5V output down to 1.8V for the input to the GSM module - but it cannot get the GSM module's 1.8V output up to the 5V required by the microcontroller's input! Similarly, if the GSM unit has an RS232 output, a simple resistive divider will still feed -5V to the microcontroller for the RS232's negative level! |
| Topic | Author | Date |
| rs232 serial communication and microcontroller | 01/01/70 00:00 | |
| Cross-post | 01/01/70 00:00 | |
| GSM Module serial interface | 01/01/70 00:00 | |
| Not true | 01/01/70 00:00 | |
| Ive corected my post | 01/01/70 00:00 | |
| That's confusing! | 01/01/70 00:00 | |
| A case in point | 01/01/70 00:00 | |
| depends... | 01/01/70 00:00 | |
| more spesipic | 01/01/70 00:00 | |
| Set up matrix | 01/01/70 00:00 | |
| More info required! | 01/01/70 00:00 | |
| Layers | 01/01/70 00:00 | |
RS232 and Serial Communications | 01/01/70 00:00 | |
| Resistor is NOT an answer! | 01/01/70 00:00 |