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Showing posts from October, 2017

My serial port PIC programmer doesn't work!

It seems that the 'issue' that plagued us when NT4 came out is still with us. At least for 'newbies' or others like me who was given a serial/RS232 PIC programmer. 
The other 'issue' is that most new hardware, laptops and desktops, don't have serial ports. So the 'user' is forced to use a USB to RS232 adapter. This 'adapter' does not have the correct RS232 voltages on its pins... So any circuit connected to it does not get the correct voltage [higher than 5 Volts]. For example: Several packet modems would not function with the later models [9 pin] interfaces. These modems were [correctly] designed to connect to a 'real' RS232 interface. Which goes negative with respect to the ground [0V] pin. The interface circuit required the pins to go below -3 Volts for correct switching. This is to improve the noise immunity of the circuit.
With the PIC programmers, it is a case of cheap [sorry cost effective] design. So that the programming voltag…