24" Wall Clock

From OpenCircuits
Revision as of 17:36, 6 September 2007 by (talk)
Jump to navigation Jump to search

msi geforce fx 5900 ultra bst30 batteria sony ericsson rickmansworth mariasole poker book disegno di ricerca sony hc22 thef propfan corsi istruttore fitness atoll hdd registratore argobba garmin streetpilot 2660 verbatim dvdrw codex riassunto della lupa mark romanek the work of director batteria creative zen micro dmc hirsute woman scale in ferro battuto the hallo www 4men ro batteria liion lofra cucina danza classica portanti a macchine per colata continua cavalcata valchirie seat cordoba 19 sdi 4p se assicurazione monza annunci con viva street it dvd sony dvppq2 selen hardcore vai a google convertitore scart vga international registry super fighetto instant tv fm pci televisore digitale terrestre dissipatore p4 www orgasmo de animales com barnes thomas tv porno rispetto impiego a brescia e provincia galway shopping nikon 5900 foto tessere di sondrio cisl frosinone testo calma e sangue freddo di luca diri stampante laser colori a4 rete carlo petrini servizio militare acerina portatili 14 pollici suzuki swift 13 ddis router adsl linksys coralis citroen c3 city suv friends anno 3 carta stradale emilia romagna il funambolo intrigo cuba elle m regardait guerra strategica ragazza orbassano valutazione camper usati videos de zoofilia pray pray pray capello prodotti vendita dvd adul hung nhung ambulanza foggia esecuzioni irak gratis scaricare gps 76 map playa del carmen ozone mia hi hi topfield pvr 5000 scarica video liste annullate in calabria elezioni com roccafranca quebec bmw treviso ruben blade midi vodafone pgr yamaha psr3000 gemelli diversi video clip vacanza al mare toscana de la ola filmati uccisi in iraq salute gambe iso autoradio sara ricci foto emma button nochia malag www alfasport net nome cane costo bollo auto rnb2 imogen hide and seek bucalo xiao xao 10 compatibili stella cometa disco fisso esterno mp3 free hello kitty griffin lapel gioco da disegnare star wars la trilogia la donna dai due volti blockbuster in italiano possibili ritardi per gran turismo 4 in europa natale disney vaginale pt cruiser diesel nokia 1 3 megapixel cheap wellbutrin zanaflex online zyban online fioricet online propecia mtv ringtones cheap lisinopril paxil online kyocera ringtones ultram online free mono ringtones didrex hydrocodone lorazepam online polyphonic ringtones verizon ringtones free nextel ringtones cheap ambien music ringtones nokia ringtones free sonyericsson ringtones pharmacy online online free ringtones cheap vicodin diazepam online alprazolam online ultracet meridia online flexeril online lortab norco online hoodia sagem ringtones nexium soma cheap cyclobenzaprine zoloft online jazz ringtones free cingular ringtones free motorola ringtones midi ringtones cheap carisoprodol cheap hgh sony ringtones tramadol phentermine online cheap albuterol cheap vigrx qwest ringtones diethylpropion free sprint ringtones cool ringtones clomid online adipex online cheap levitra cheap xenical cheap sildenafil punk ringtones mp3 ringtones xanax online ativan online prozac online cheap celexa cheap ortho tenuate free samsung ringtones lipitor online free ericsson ringtones sharp ringtones free alltel ringtones valium online tracfone ringtones free sony ericsson ringtones rivotril online clonazepam free real ringtones cheap cialis viagra online free funny ringtones free wwe ringtones {| align=right |- |

Error creating thumbnail: Unable to save thumbnail to destination

|} Site - very comprehensive and meticulous from all points of view, it�s good! Just excellent website, I'm sure!

philadelphia gay massage | nude gay boys | hot gay guy | hard gay men

I just don't have much to say lately. Eh. Not much on my mind lately.

lesbian scene | lesb | forced lesbian | lesbian tribadism

Clock Control

Who wants to set the real time when we've got GPS to set it for us?! :) I am going to use the Lassen iQ to get a time lock and use a couple buttons to get the local time from that.

We need to control 23 channels 18:88:

  • 1 has two segments, but the entire number is either on or off
  • : is always on, but we may way to flash it for seconds
  • 888 21 channels

I decided on 25 channels just in case I need some extra ['flare']. Perhaps an alarm of sorts. 'Beer Time' alarm at 4:30pm? We've got to keep our options open...

The need for 25 I/O pushed me towards the PIC 16F877A:

  • Easy to program (I've got a big code base)
  • Has enough I/O
  • It can be bootloaded!
  • It's got an RTC (when you add an external 32.768kHz xtal)
  • UART to read the incoming GPS NMEA from Lassen iQ

ToDo : It's possible to reduce the number of channels by multiplexing. A gain cost is also possible by multiplexing digits, less cm2 of board, less expensive components, less comsumption. 7 segments x 4 digits (remenber the 24:00 time format from 00:00 to 23:59) = 4 channels for digits and 7 channels for segments = 13 wires 1 for ":" 4 for extensions = 18 wires. Some other components like CA3161 (bcd to 7seg) can also reduce necessary wires on PIC for displaying about 4 4 1 4 = 13 wires.

Light Control

Well if the PIC 16F877A has got the timing and control down, how exactly do we turn on/off the light stick?

Since the sticks only pull 60mA, we can use cheap BJT transistors. Let's go solid state! Many itty-bitty SOT-23 SMD BJTs can handle up to 1A with a max input of 40V. The maximum power output is 350mW though. Luckily, when forward biased, the MMBT2222 has around 0.5V drop.

So 60mA with 0.5V drop, we are looking at 30mW dissapation. That's atleast in theory. I'll believe it when I see it of course. For the time being, I'm going to assume this will work...

All I need is an NPN BJT for each channel:

Error creating thumbnail: Unable to save thumbnail to destination

While this should work, it's going to leave a bunch of connections with one pin 'hot'. A better design would probably utilize a PNP connected to RAW. Ehh - no big deal.

If you're planning to use a beefy light source, like Neon or super powerful LEDs, you could easily use the same setup to control a relay. Relays can handle 5-20A in some cases, are relatively cheap, and sound really cool! The only problem is they are big. And for this project, we wanted a relatively small control board. The next rev may use beefy 5A relays to toggle all sorts of potential snazzy light sources.

Board Layout

The PIC is connected to 25 channels, the GPS, a couple buttons, and a status LED. Here's the current layout in all its random glory:

Error creating thumbnail: Unable to save thumbnail to destination

You can see it's a bit dense, but the polarized two-pin connectors should make it easy to attach the light sticks. Everything was SMD to ease the assembly as much as possible. It's much easier for us to do solder paste with a stencil and SMD devices than it is to bend 25 resistors and solder 25 BJTs into place, then clip all the leads. PTH is actually pretty time consuming. I digress...

There is a switch to multiplex the PIC's RX UART inbetween Debugging and listening to the GPS unit. Be sure to use Port 2 on the Lassen iQ if you want NMEA output (4800bps by default).

Things to Improve

Nothing at the moment. We have to wait for all the parts to come in. Should be about 4 weeks.

We may need a cover on the light sticks to give more of an opaque presentation. TBD.


SFE Wall Clock Main Board Schematic

Channel Control Schematic

SFE Footprint Library

FP Name: All sorts of FPs used.

Supplier Info:

Related Items: