If you are seeking code examples of how to drive the 74595 then see here; https://www.arduino.cc/en/tutorial/ShiftOut that should get you on the way, there should be an example of two 74595s cascaded together. It will show how to drive the three signals required on the 74595 to set up the DATA value, CLOCK it into the 74595 and LATCH it to the output pins (just my terminology). For circuit design and pcb layout take a look at easyeda.com - everything you need is there.
On Friday, 8 November 2019 06:48:42 UTC, Christine Thompson wrote: > > Hi David, > > > > I have made some progress, purchased the 74HC245 and 74HC595 chips and > breadboarded the circuit you supplied. I have two questions which I would > > appreciate answers to: > > > > 1. Your diagram shows lines LD,SCK, and MOSI on the lower 74AC595 and > LD, and SCK on the upper 74AC595, how are these lines attached to the > Arduino data lines? > 2. Do you have an example of a simple test Arduino program that I can > examine to better understand the software I will need to write. > > > > Once I get the above working I would like to create a PCB board rather > than using my existing construction method, can you suggest suitable > schematic / PCB layout software? > > > > Regards, > > > > Christine > > *From:* [email protected] <javascript:> <[email protected] > <javascript:>> *On Behalf Of *David Forbes > *Sent:* Tuesday, November 5, 2019 6:40 PM > *To:* NeoNixie <[email protected] <javascript:>> > *Subject:* Re: [neonixie-l] Re: 7 Segment Common Anode Display > > > > Here is a schematic diagram that I just whipped up. It uses the SPI > signals to shift data into the anode and cathode drivers. > > The software needs to write two bytes (digit then segments) to the SPI > port, then write LOW then HIGH to the LD/ signal. > > > > The digit byte must have one bit low to select a digit. > > > > > > > > On Mon, Nov 4, 2019, 9:48 PM Christine Thompson <[email protected] > <javascript:>> wrote: > > Hi David, > > > > Thanks for the information. My last clock used 8 X ICL/1-1-8 VDF displays > using the MAX6921 chip and works fine, silly me to assume that the same > chip would also work with 7 segment displays, started to worry when I > noticed in the MAX6921 datasheet that the minimum output voltage was 8V. In > all the clocks I have made I have used either the MAX6921 multiplex method > or K155 IC chip Direct drive method. > > > > So I need to go back to basics for this clock. I can certainly purchase > the shift registers and Octal buffers from E-Bay, however in the meantime > could you suggest a link to an article / document that describes the basic > method of how this system is constructed. > > > > Regards, > > > > Christine > > > > *From:* [email protected] <javascript:> <[email protected] > <javascript:>> *On Behalf Of *David Forbes > *Sent:* Tuesday, November 5, 2019 4:48 PM > *To:* NeoNixie <[email protected] <javascript:>> > *Subject:* Re: [neonixie-l] Re: 7 Segment Common Anode Display > > > > There is no reason to use a fancy Maxim chip for an LED display. Two > 74HC595 SPI shift registers and two 74AC245 octal buffer chips will do the > job. One for the anodes, one for the cathodes. > > > > > > On Mon, Nov 4, 2019, 3:41 PM gregebert <[email protected] <javascript:>> > wrote: > > The Maxim part you mentioned is for VFD's, and it looks like it can run as > low as 8V. If you use it to drive the anode of your LEDs, you run the risk > of exposing the logic driving the cathodes (segments) to roughly 6 volts > (the LED has about 2V of forward bias). > > > > If the Arduino has 5V-tolerant I/O pins, you will have problems because > there will be a current path through the LED to the 5V supply even if your > LED is off; this is the parasitic-diode path in the IC that forms part of > the ESD protection network for pins. > > > > Before going any further, do you have a datasheet for the LEDs ? 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