I'm working on a temperature sensor project. The analog from the sensor will be converted into digital signal. The digital signal then will be transferred via RF module. From the RF receiver, the signal will then be displayed on two 7-segment displays. (only display from 0 degree up to 99 degrees.. other than that the displays are blank)
Now, here's how I plan to tackle the problem. The sensor is a thermocouple sensor. The A/D converter will convert the analog signal into 8-bit digital signal. The 8 bits will then go through a parallel-in/serial-out shift register to allow the signal to be transmitted via RF. At the receiveing end of the RF module, there will be serial-in/parallel-out shift register so that the signal will be in parallel. The 8-bit signal will then be decoded by two SN74LS47 decoders, where SN74LS47 decoder is BCD-to-7-segment Decoder. The first 4 outputs of the shift registers will go to one SN74LS47 decoder and the last 4 ouputs of the shift registers will go to the other SN74LS47 decoder. Each of the two decoders will then produce 7 outputs that will drive a 7-segment display.
But I'm not really know about the following issues:
1. The A/D converter will convert voltage difference from the sensor. So, for example, if the temperature sensed 65 degrees, the voltage produced is for example, say 15mV. Then the digital signal produced from the A/D converter will represent 15mV. Then how do I scale the signal back so that at the displays, the number will be 65?
2. The RF receiver will receive signals continuously. Each signal will be represented with 8 bits. And the signals will be serial signals, since the signal just came out of the parallel-in/serial-out shift register before being transmitted. How do I determine which bit is the first bit of one particular 8-bit signal and which bit is the last bit of that particular signal? Because I realized that the if one signal arrived at the RF receiver, then the next signal will follow. How do I diffrentiate between the two signals?
Now, here's how I plan to tackle the problem. The sensor is a thermocouple sensor. The A/D converter will convert the analog signal into 8-bit digital signal. The 8 bits will then go through a parallel-in/serial-out shift register to allow the signal to be transmitted via RF. At the receiveing end of the RF module, there will be serial-in/parallel-out shift register so that the signal will be in parallel. The 8-bit signal will then be decoded by two SN74LS47 decoders, where SN74LS47 decoder is BCD-to-7-segment Decoder. The first 4 outputs of the shift registers will go to one SN74LS47 decoder and the last 4 ouputs of the shift registers will go to the other SN74LS47 decoder. Each of the two decoders will then produce 7 outputs that will drive a 7-segment display.
But I'm not really know about the following issues:
1. The A/D converter will convert voltage difference from the sensor. So, for example, if the temperature sensed 65 degrees, the voltage produced is for example, say 15mV. Then the digital signal produced from the A/D converter will represent 15mV. Then how do I scale the signal back so that at the displays, the number will be 65?
2. The RF receiver will receive signals continuously. Each signal will be represented with 8 bits. And the signals will be serial signals, since the signal just came out of the parallel-in/serial-out shift register before being transmitted. How do I determine which bit is the first bit of one particular 8-bit signal and which bit is the last bit of that particular signal? Because I realized that the if one signal arrived at the RF receiver, then the next signal will follow. How do I diffrentiate between the two signals?