| ??? 05/09/08 17:45 Read: times |
#154626 - that's 7-segment glass ... requiring no controller Responding to: ???'s previous message |
You can drive a 7-segment LCD directly from your MCU. It's pretty simple. If you drive the backplane at one level, you must have the active segments driven to the opposite polarity. The LCD is an AC device, so you must alternate the polarity of the backplane and segments at a moderate rate, on the order of 50 Hz or thereabouts.
This drive is normally provided by driving the backplane with a low frequency clock, as already said, at about 50 Hz, through an XOR gate for each segment. If you don't mind changing the polarity of the segments and the backplane at the MCU, you won't need the XOR's. There are other "tricks," too, which work on some LCD glass. These involve setting the backplane voltage with a resistor divider and simply reversing the polarity of the segments. This saves a few steps. The LCD provider should have plenty of information about the various applicable tricks. The power consumption is extremely low. RE |
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check this | 01/01/70 00:00 |