#garfield Logs

Mar 18 2013

00:00 rue_house I'm nt talking about using them for displays tho, just pwm
00:01 useless-afk and they are $1.10 (with s&h) each best case on ebay, and i picked up ochal latches for 10 cents each that i can vary brightness with the avr's pwm output strobing the OE of the latches
00:01 useless-afk ummm
00:01 useless-afk i don't overstand
00:02 rue_house servomotors, power supplies
00:02 rue_house its 14? bit pwm per channel
00:02 useless-afk how do you make a led driver be a power suply?
00:03 useless-afk 14bit is overkill, ntsc/pal tv standard was 8 bit
00:03 rue_house you just use the pwm output to a buck converter
00:03 rue_house 1 of its 16 channels
00:04 useless-afk why can't i use a 85 cent tiny44 to pwm the buck convertor?
00:04 rue_house you can
00:04 rue_house that chip was 50c on ebay
00:04 rue_house (tho I bought 20 of them)
00:04 useless-afk it was $2.20 for 2 best price i saw
00:04 rue_house oh...hmm
00:04 useless-afk $1.20 + $1 s&h
00:04 rue_house uh, its still cheaper per channel?
00:05 rue_house :/
00:05 useless-afk i still do not see how you'd use it for anything else
00:05 e_house tries to find a leg to stan
00:05 rue_house its a slave 16 channel, 14 bit, pwm genorator
00:06 useless-afk so would a 18bit latch be, and i have those too
00:06 rue_house okok I just thought it might be of interest to ya...
00:06 useless-afk but you cannot tell me why pelase?
00:07 rue_house drat, its after bedtime and I didn't test any monitors
00:07 rue_house kat, it seems like a handy chip
00:07 rue_house to me
00:07 useless-afk i wish i could see what you are doing with it
00:07 rue_house granted my projects are of a different nature
00:08 rue_house I'm pondering using it for the pulse control on the washing machine valves
00:08 rue_house or 16 channel servo loop controlelrs
00:08 useless-afk are you taking time off the 30Mhz to program the eeprom settings difefrently for each bit? eeproms take time to set and change, near as i can tell you cannot write the pwn for each bit separaely and directly
00:08 rue_house nono
00:08 rue_house the eprom is just for offset junk
00:09 rue_house dont need that
00:09 rue_house you can clock in the new values at the 30Mhz
00:09 rue_house iirc
00:09 rue_house and it uses an external pwm clock, so its really flexable on the output freq
00:10 eless-afk calcul
00:10 useless-afk assuming you candrive it's 30Mhz inputs with a 20Mhz avr................
00:10 rue_house the update rate was quite reasonable iirc
00:10 rue_house its synchronous, you dont even have to clock it in that fast
00:10 useless-afk lets say you are bit banging at 5Mhz from a 20Mhz avr.........
00:11 rue_house I'm gonna go test one of the 12 monitiors before bed, biab
00:12 useless-afk if the instruction and bit id number is 16 bits, and you change 16 bits, your rate of change is 19k changes/sec
00:29 rue_house buddy only updates pwm values at 8khz
00:30 rue_house which is overkill cause the pwm freq is lower than that (iirc)
00:31 rue_house hmm I thik my boiler overheated and dumped
00:34 rue_house nope
01:32 useless-afk o
01:35 useless-afk the fire died out, there must be 1/2 gallon of rust in that tank i cannot get out because of all the baffles, but it's now dry as a bone, there's no more sludge in it
01:35 useless-afk got rid of termitey wood before they reinhabited it this Spring, and made the tank recycleable too
01:38 useless-afk this image may change at any time, but atm, the weather is doing donuts across the state : http://icons-ak.wunderground.com/data/nids/BMX19_thumb_t.jpg
09:21 useless-afk so if the olde svga monitors like i use are being phased out, and they are fed 50Mhz to 400Mhz RGB but feed their LCD with digital, why aren't we ankle deep in cheap triple 400Mhz ADC chips now?
09:28 useless-afk -----------------------------------------------------
09:28 useless-afk AL875 ; Triple High Speed, 8-bit Analog-to-Digital Converter
09:28 useless-afk � High speed 8-bit ADC up to 110MHz conversion rate
09:28 useless-afk � Support display resolution up to 1280x1024 at 60Hz refresh rate
09:28 useless-afk � Low power dissipation (0.9W typical at 3.3V, 110MHz)
09:28 useless-afk � 0.6~2.0V p-p analog input range
09:28 useless-afk -----------------------------------------------------
09:35 useless-afk rue, you like tricks with chips, how's this: take a http://www.ebay.com/itm/ADS5120-8-Ch-10-Bit-CMOS-Analog-Digital-Converter-ADC-/370202913589 and daisey chain each adc input to the preceeding one with 2.5ft of twinax, and run the chip at 40Mhz, you'd have the equivalent sample rate thru time of one per 3 ns, or 320Msps
09:37 useless-afk the chip actually samples every 25ns, but each 2.5ft of line lags each adc input by 3ns, 3ns x8 = 24ns
09:37 useless-afk tweak the length to be accurate based on your choice of pcb material and twinax or coax
09:38 useless-afk 320Msps for $13 is a great deal
09:43 useless-afk i didn't read the datasheet yet, but if it's 40Mhz @ 8 output ports, interfacing it to cheap ram would be trivial
09:43 useless-afk -----------------------------------------------------
09:54 useless-afk http://www.ebay.com/itm/NOS-AD9883AKST-140-AD9883AKSTZ140-ADC-Triple-140Msps-8-bit-Parallel-LQFP80-x-1pc-/160841714100 is $7 with s&h for 1st one, $5 each one after that
09:55 useless-afk AD9883A is triple 8bit parallel out also
10:09 useless-afk TDA8707 is 6bits, that's +/- 1.6%, the oscopes are 3%
10:11 eless-afk talkes in alphabet soup for a sec: "/me wants a RGB SVGA ADC A
10:15 useless-afk yipes : Search Description : 'triple video adc ' - Total: 6765 (1/10) Pages
10:16 useless-afk http://category.alldatasheet.com/index.jsp?Searchword=TRIPLE%20VIDEO%20ADC
10:20 useless-afk THS8135PHP {THS8135} TRIPLE 10-BIT 240 MSPS DAC IC <<== $13
10:22 eless-afk tries to pipe alldatasheet thru
10:26 eless-afk is fascinated by the possibility of using a 100Mhz oscope to build a 1.6 Gsps digital storage
10:27 useless-afk $22 of adc chips (4 triple adc chips @ 140Mhz)
10:29 useless-afk holycrap, Atmel makes a 500Msps adc
10:29 useless-afk http://html.alldatasheet.com/html-pdf/94090/ATMEL/TS8308500/128/1/TS8308500.html
10:40 useless-afk ----------------------------------
10:44 useless-afk problem is 7ns per sample is gonna need some fast rams
10:45 useless-afk or, fast latches and parallel feed slow rams ;-)
11:11 eless-afk has a bad sneaky feeling these chips do not sample continuously, they quit during hsync and v
15:56 useless-afk http://classic.wunderground.com/radar/radblast.asp?ID=BMX&region=c4&lat=33.59627914&lon=-86.32241821&label=Pell%20City%2c%20AL
15:56 useless-afk already had 1/2 inch hail, and it isn't even here yet
15:56 useless-afk power blinky, going to power down
16:47 Tom_itx yay, the Viton seal appears to have worked
16:47 Tom_itx $.50 opposed to the $25 dealer part
20:28 Lola8088
20:31 Tom_itx �
23:55 rue_house ok I got one more printer stripped and two power supplies
23:55 rue_house filled another garbage can, ... er most of it was overflow from yesterday
23:55 rue_house ok 3 mins to spare to make supper