microcontroller 8051 rf tx rx encoder decoder


Posted on Feb 5, 2014

The problem is when i connect the 8051 to the encoder the data send is not received at the receiver but as soon as the 8051 connections are removed the transmisison works perfectly. thus manually the RF communication works perfectly i. e the 8 bit data which i give manually at the encoder is perfectly send and then later received at the decoder sid


microcontroller 8051 rf tx rx encoder decoder
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e Is some sort of interfacing required b/w encoder-ht640 and microcontroller 8051 or at the receiver side b/w the decoder-ht648l and 8051. help me plz its urgent In the 8051 architecture ports 1, 2, & 3 are quasi-bi-directional ports. They have weak pullups, and no data direction registers. They require no configuration and have 1`s written to them at reset making them inputs or "weak" 1`s They will sink a couple of milliamps, but source only several tens of microamps. In the 8051 architecture ports 1, 2, & 3 are quasi-bi-directional ports. They have weak pullups, and no data direction registers. They require no configuration and have 1`s written to them at reset making them inputs or "weak" 1`s They will sink a couple of milliamps, but source only several tens of microamps. i checked it separately also i. e only 8051 connected to encoder and TX and only the decoder and RX at the other end but the decoder is not able to read the data send by the 8051 through the encoder. A cursory review of the HOLTEK HT640 Datasheet reveals the the TE pin on the HT640 is a CMOS input which is pulled low. This is problematic since the 8051 has outputs with a weak pullup. When the 8051 pin P3. 3 is at a `1` this will form a voltage divider and the actual level on the P3. 3/TE net will depend on the relative magnitude of the pullup and the pulldown. When P3. 3 is low all will be fine and you should get a solid low.




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