PIC Vietnam - View Single Post - saving you costs: 4-digit LED display drive using 16f54

**tetsu-jp** · 20-01-2012, 03:36 PM

I had the circuit running for a while and overheating/burnout wasn't an issue at all.

Then I made PCBs actually.

I searched the net many people actually use big circuits for 7segment drive, even if they use multiplex they still use transistors+resitors, quite an effort.

7segment patterns by tetsu-jp * has new modem, on Flickr

the patterns to drive the display, avoiding I/O remapping. Not all pins can be used freely, the ICSP pins only can be used for cathodes sink. If there is "High" potential, it will be blocked by the 7segment LED!

serial communications circuit by tetsu-jp * has new modem, on Flickr

Test PCB for serial communcations, 2x PIC 16f54

2 microcontrollers system by tetsu-jp * has new modem, on Flickr

Using a GAL programmer module for the 2nd PIC

The code for the 16f54 is a bit exotic since a ready signal must be polled, and data can only be sent during blank phases (8 phase drive every second phase is blank).
To sell this PCB a PIC with hardware serial port would be better, since it is more complicated to use software-based serial communications.

It is interesting to search the net and to come accross many circuits which have amateur/hobbist level, many of them use very old PIC models, for instance 16f84 or 16f8xx.

I do not see it very often that people actually look at their circuit, then rebuild it again even 3 or 4 times to improve the design.

20-01-2012, 03:36 PM	#6
tetsu-jp Đệ tử 1 túi Tham gia ngày: May 2011 Nơi Cư Ngụ: nước Đức Bài gửi: 18 :	I had the circuit running for a while and overheating/burnout wasn't an issue at all. Then I made PCBs actually. I searched the net many people actually use big circuits for 7segment drive, even if they use multiplex they still use transistors+resitors, quite an effort. 7segment patterns by tetsu-jp * has new modem, on Flickr the patterns to drive the display, avoiding I/O remapping. Not all pins can be used freely, the ICSP pins only can be used for cathodes sink. If there is "High" potential, it will be blocked by the 7segment LED! serial communications circuit by tetsu-jp * has new modem, on Flickr Test PCB for serial communcations, 2x PIC 16f54 2 microcontrollers system by tetsu-jp * has new modem, on Flickr Using a GAL programmer module for the 2nd PIC The code for the 16f54 is a bit exotic since a ready signal must be polled, and data can only be sent during blank phases (8 phase drive every second phase is blank). To sell this PCB a PIC with hardware serial port would be better, since it is more complicated to use software-based serial communications. It is interesting to search the net and to come accross many circuits which have amateur/hobbist level, many of them use very old PIC models, for instance 16f84 or 16f8xx. I do not see it very often that people actually look at their circuit, then rebuild it again even 3 or 4 times to improve the design.