I am about to make a clock with the B7971 segmented Nixie tubes using a 6 digit controller chip, the?DS32KHZ and super cap I bought from Moses, www.neonixie.com a while back. see
Any help with using this controller and the above tubes would be of much help.
Here are my questions:
I guess all I need to do is substitute the 74141 ICs with the DS8880 ICs and connect to the appropriate pin segments on the B7971. ?Is this correct??The problem is that the truth table for the DS8880 driver may not match the truth table for the 74141 driver. I have posted both data sheets.
The biggest puzzle to solve is figuring out how to utilize the features of this controller for leading zero blanking, PWM dimming, cross fade and timed display off to preserve tube life with the DS8880 in place of the 74141 driver. I am not sure how to work with the Truth Table and BI/RBO or RBI input pins on the DS8880 driver in relation to the "blanking pin 27" on the controller to make this all work. The data sheet for the DS8880 states "The Blanking Input provides unconditional blanking of any output display, while the Ripple Blanking pins allow simple leading- or trailing-zero blanking."
This is all Moses can say:
DIGIT BLANKING
By default the controller `blanks' digits by outputting all ones on the BCD lines. Blanking is required for PWM dimming, leading zero blanking and cross-fading to work properly. This default setting works well with 74141 Nixie Driver ICs, but if you are using other display drivers you might want to review the Digit Blanking option (#53). For example if you are using the controller as a simple LED binary clock, you would want to set this option to either 3 or 4. This will result in a low output on the BCD lines during dimming, correct for individual LEDs. A separate blanking output pin is also provided (pin 27), which can be used for dimming display drivers with separate blanking inputs. It can be set for low or high blanking.
● Option #53: Digit Blanking Method.
Controls the digit blanking method and blanking output pin (#27). See assembly instructions for details.
NOTE: This option refers to the logic levels used to BLANK (or turn off) the display.
- 1: BCD all high, BLANK pin high
- 2: BCD all high, BLANK pin low (default)
- 3: BCD all low, BLANK pin high
- 4: BCD all low, BLANK pin low
NOTE: If using the blanking output pin of the controller wired to all the displays, the clock will not cross-fade or blank a leading zero properly since each digit needs its own blanking output. A simple solution is to hook up a NAND gate (for drivers with low blanking inputs) or a AND gate (for drivers with high blanking inputs) to the C and D connection of each BCD output (with BCD blanking set to high). Run the output of the gate to the digits blanking input. This works because
BCD C and D will only be high when the controller commands a blank digit.
NOTE: If you will be using the blanking pin, it is recommended to install a 3-way jumper in order to disconnect the drivers from the blanking output and connect them to a logic level that will result in an active display. This can be used in case the digit blanking option is accidentally modified to blank the display.
If anyone can figure this out, I would be much appreciative. Moses will not give specific "engineering" advice due to liability.
Thanks again for all your help.
Dan
