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It is very easy. Connect the ULN2803 inputs to outputs of 74HC595 and connect SH_CP, DS and ST_CP of 74HC595 to your Microcontroller. Now just send 8 bit data to operate the relays by shifting the 8 data bits to HC595 using SHCP and DS and then provide one clock to ST_CP. This will store the data at the output of HC595 which will turn ON/OFF the ULN2803 and hence the Relays. next when you want to turn OFF or ON the relays then use and and or operators with a variable which holds the relay port data.
How many relays do you want to control and what MCU are you using ? What is your Crystal frequency ?
Both devices have detailed datasheets. Did you read through them? Did you draw a schematic?
Did you do a search on similar projects. (I assume you are not the first one to combine a serial-parallel shift register and a driver IC)
Thanks for your replying, acutally I want to switch different channal acquired voltage and send to COM Port compared.in my mind by relay controled but without do it.I want change other way to control multichannal by 74HC595 and ULN2803.How to compiled it? THX!
Sorry, I can't understand what your are saying. To read ADC you don't need relays. Do you want to control different relays based on the adc values and using 74HC595 and ULN2803 for Relays ?
Yes ,I want to acquired voltage for different test point of PCBA board,if have twenty or thirty test points so using 74HC595 and ULN2803 controled Relays for different test point.Do you have else idea for the issue? Thanks!!
I will give you a code but I need 2 days to write the code and I will write code using mikroC PRO 8051 because I don't have Keil C51. Zip and attach your complete Keil C51 project and Proteus file.
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