Hi...
I'm building a small project in which I want to fully and independently control two seven segment display using a minimum number of pins. First I've planned to use two 8-bit shift registers, "inline" forming a 16-bit shift register, and directly connected to the displays. In order to reduce the number of ICs I though in using only one 8-bit shift register and some kind of multiplexing to control one display at a time. Multiplexing is done by connecting the common pin of each display to one of the I/O pins so that only one display is working at a time.
My first question is: a transistor is needed when connecting the common pin to the I/O port? Or because the current is furnished by the shift register it isn't needed anymore?
If I used only one I/O pin for both displays (plus a inverter) when data is being put in the shift register will a glitch appear in the appearance of the display?
Thx in advance...
I'm building a small project in which I want to fully and independently control two seven segment display using a minimum number of pins. First I've planned to use two 8-bit shift registers, "inline" forming a 16-bit shift register, and directly connected to the displays. In order to reduce the number of ICs I though in using only one 8-bit shift register and some kind of multiplexing to control one display at a time. Multiplexing is done by connecting the common pin of each display to one of the I/O pins so that only one display is working at a time.
My first question is: a transistor is needed when connecting the common pin to the I/O port? Or because the current is furnished by the shift register it isn't needed anymore?
If I used only one I/O pin for both displays (plus a inverter) when data is being put in the shift register will a glitch appear in the appearance of the display?
Thx in advance...