#seven-segment display

[pickanmixes]

Yeen in the material world

[akita-ken]

dashClock update #1.5

in line with my standard procedure of drafting up circuit diagrams for projects before beginning actual hardware work, i've been working on one for the dashClock. however do note that the one i've uploaded here is incomplete - it's missing some of the connections from the ATTiny84 uC to random peripherals (such as an LDR and a buzzer). it's also missing all Vcc connections on every IC.

when coming up with drafts for circuit diagrams i usually take a modular approach to the construction of the system. therefore the seven-segment displays (SSD) and MAX7219CNG would form the 'display module' and i'd tackle that first. the DS1307+ and DS32KHZ would form the 'clock module'. the MAX603CPA and MAX608EPA would form the 'power module'. so on and so forth (you get the idea). basically, all three modules are complete in this diagram but the interconnects between them are not entirely done, therefore i'm labeling this post as an incremental update hence the .5 increment. (the #2 update will probably include an updated diagram with everything connected).

after careful consideration i've decided not to use the MAX690A supervisory IC to handle the battery backup switchover since i found it to complicate the circuit unnecessarily. furthermore, careful examination of datasheet revealed that it was designed to preserve contents of volatile memory and therefore was only about to source about 80mA of current or so (definitely not enough for my purposes). therefore i've decided to use the commonly-used diode-OR setup using schottky diodes instead of regular BJTs. the voltage drop of the 1N5817 is only about 0.3V which is small enough that it will not adversely affect the operation of the SSDs.

[akita-ken]

dashClock update #1

okay, so i thought i'd just give a quick starter update as to the progress of the dashClock project. this is basically a spin-off from the original project prototype into something a little easier (relatively speaking). that said, work *has* begun on the dashClock and i estimate the progress to be hovering around the 35% to 45% mark as of now. i've decided to use a socketed approach for most if not all of the board components for easier troubleshooting and debugging and the cabling for the LED driver circuit is done (i.e. the seven-segment displays have been wired to their controlling IC, in this case a MAX7129CNG). i am currently in the process of wiring up the ATTiny84 microcontroller to the DS1307+ real time clock as well as it's ISP socket (yes i even used a socket for the ISP headers!). one thing i've realized about using sockets for everything is that they elevate components a short distance off the board and this in essence frees up space underneath for other components/random cabling. in fact, the MAX7219CNG LED controller IC rests snugly underneath the seven-segment displays and this shortens to the total length of cabling required to connect them together as well. not to mention, it hides the IC and generally gives it a neater look.

the only remaining component i'm waiting for which hasn't arrived is a breadboard/perfboard-compatible DC barrel jack plug adapter that i had great trouble finding anywhere else other than at sparkfun and adafruit, so finally bit the stick and just ordered 6..

as this week is a short weekend and also due to the fact that i've been more or less caught up with my major room reorganization, i've not had time to continue the project. however once i've cleared up and prepared a small part of my desk as a dedicated soldering area, i'll probably continue with the remaining components. as of now, i forecast a 60%-70% completion rating by the next update.