| ??? 07/07/05 14:59 Read: times Msg Score: +1 +1 Informative |
#96778 - Isolated RS-232 with microcontroller Responding to: ???'s previous message |
Here is isolated RS232-TTL converter which requires standard and easily available parts and provides full isolation at upto 115200 bps. For PC side, the circuit draws its power from RTS and DTR of PC COM port which is regulated by a LDO type regulator (having very low quiscent current.). For microcontroller side, power is supplied by microcontroller board.
If someone wants to try it, here are some points which should be taken care about. 1) U4 must be an LDO type with low quiscent current. No 7805 will work. 2) D1 and D2 should be schotky diodes (they have low Vf.) 3) Either RTS or DTR should be set at +ve voltage for the circuit to work. (If full baud rate is required, set both at +ve) 4) MAX3232 can also be used, if so change LP2950-5.0 to LP2950-3.3 5) A buffer from TX to U2 is recommended. 6) DB9 connector shown is PC COM port i.e 1 to 1 straight. 
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| Topic | Author | Date |
| Serial Connector Problem! | 01/01/70 00:00 | |
| Grounding | 01/01/70 00:00 | |
| Grounding | 01/01/70 00:00 | |
| Isolate | 01/01/70 00:00 | |
| B+B | 01/01/70 00:00 | |
| Thanks Andy and Steve | 01/01/70 00:00 | |
| Grounding! | 01/01/70 00:00 | |
| Isolated RS-232 with microcontroller | 01/01/70 00:00 | |
| Just a thought... | 01/01/70 00:00 | |
| picture too big | 01/01/70 00:00 | |
| Sorry for a huge picture | 01/01/70 00:00 | |
| Here is isolated RS232-TTL converter | 01/01/70 00:00 | |
| Info: Members posting pictures | 01/01/70 00:00 | |
| Standards | 01/01/70 00:00 | |
| Re: Standards | 01/01/70 00:00 | |
| is that really less than $3.20 | 01/01/70 00:00 | |
| Re: it that really less than $3.20 | 01/01/70 00:00 | |
| 1000 up prices | 01/01/70 00:00 | |
| that affect everything | 01/01/70 00:00 | |
| Re: that affect everything | 01/01/70 00:00 | |
| reinventing the wheel | 01/01/70 00:00 | |
| will this suffice? | 01/01/70 00:00 | |
| for me, yes | 01/01/70 00:00 | |
| MAX 3250 | 01/01/70 00:00 | |
Slap in the face! | 01/01/70 00:00 |