| ??? 03/16/12 17:09 Read: times |
#186737 - I think you can do it wih one resistor. Responding to: ???'s previous message |
Connect P2.1 directly to Vout.
Most 8051 systems have a 10k resistor array as pull-ups on a port. Connect a 10k resistor between P2.1 and P2.0 as in your schematic. P2.0 = 1, P2.1 = 1 -> Vout = VCC (pulled up by regular resistor array) P2.0 = 0, P2.1 = 1 -> Vout = VCC/2 (pulled up by array, pulled down by P2.0) P2.0 = x, P2.1 = 0 -> Vout = GND (pulled down by P2.1) You need to match the value of your pull-up array to get 'half-way'. You need no external op-amps, buffers or anything (providing you are driving a high-impedance input) Alternatively, use a modern 8051 with push-pull output, or even a DAC. David. |
| Topic | Author | Date |
| Making a pulse with 3 different voltage level! | 01/01/70 00:00 | |
| No best but consider a voltage divider | 01/01/70 00:00 | |
| derivative with a DAC? | 01/01/70 00:00 | |
| derivative with configurable ports | 01/01/70 00:00 | |
| Thanks Per And Erik | 01/01/70 00:00 | |
| which derivative | 01/01/70 00:00 | |
| with an OPamp | 01/01/70 00:00 | |
| Thanks Erik | 01/01/70 00:00 | |
| So, you need to make -15V, 0V and +15V? | 01/01/70 00:00 | |
| Hi Dear Kai | 01/01/70 00:00 | |
| 74hc series | 01/01/70 00:00 | |
FPGA | 01/01/70 00:00 | |
| I think you can do it wih one resistor. | 01/01/70 00:00 | |
| Most 8051 Systems????? | 01/01/70 00:00 | |
| Well add a pull-up resistor then | 01/01/70 00:00 | |
| Would prefer to not have to match internal resistors | 01/01/70 00:00 | |
| You cannot match the weak internal active pull-up! | 01/01/70 00:00 | |
| Being pedantic. | 01/01/70 00:00 | |
| Hi David | 01/01/70 00:00 | |
| maybe a couple of mosfets ... | 01/01/70 00:00 | |
| Thanks Richard | 01/01/70 00:00 |