Despite what the symbol is, caps less than 1 uF are typically unpolarized, and >= 1 uF
are typically polarized.
what IS the minimal (but still somewhat stable/safe) components needed?
A minimum implementation would include just the chip itself.
A reasonable minimum implementation would have a decoupling cap, a crystal + two caps, or a decoupling network on the analog supply. And then more from there, based on your needs.
I have done many "chip-only" minimum implementations myself.
hi..
thanks for the reply..
this can not (should not) be a chip by itself project... IMHO..
I mean I need it to be small.. but I want it to work and be somewhat stable! lol
Since it will be running @ 3.3v & INTERNAL 8Mhz clock... I dont need the caps/crystal.......correct?
RESET pin broken out (for easier flashing/uploading)
DTR pin broken out (for easier flashing/uploading)
AREF pin (correctly set-up... I see in the schematic Crossroads posted.. he has the AREF pin connected to GND through a cap... but I do NOT need to connect to the 3.3v for a voltage refeence? Just keep it INTENRAL reference at the 1.1v or whatever?)
and of course I want to ensure that I 'correctly' set-up the battery/power input..
since there will NOT be any voltage regulator (battery supply will be within the 3-3.7v range max).. but I want it to be stable..no ripples.
follow same principles or ceramic/polarized cap on the input power lines?
@ oric_dan(333)
Despite what the symbol is, caps less than 1 uF are typically unpolarized, and >= 1 uF
are typically polarized.
thanks!.. rules like this help a noob like me.
I am still wrestling with 'decoupling'.. and 'KNOWING' when to use a certain component or not (like when to use ceramic vs polarized..etc)
hopefully I can get to a more final version tonight/tomorrow.. and I'll post for review..
appreciate all the discussion guys!
thanks!
The little ceramic decoupling caps are not polarized. Example:
Rule of thumb/general guidance: 0.1uF cap on every Vcc/Avcc pin on every part located as nearby as possible.
Aref - needs a 0.1uF cap to Gnd if you are using the internal references
See 2.2:
Lithium coin cells are usually 3.6 volts, not 3.0.
that's wrong. You can find Li-ion coin cells with a "nominal" 3.6V or 3.7V, but the vast majority of non-rechargable Li coin cells are 3.0V 404 - Duracell Batteries | AA, AAA, Rechargeable, Coin Button
this can not (should not) be a chip by itself project... IMHO..
I mean I need it to be small.. but I want it to work and be somewhat stable! lol
The chip-only implement will work and will be very stable.
update: well.. i got things up and running with a minimal/breadboard Arduino using +3.3v @ 8MHz internal clock
to be clear order of things (for me) were:
1.) hook up my Arduino Duemilanove 2009 board to USB
2.) Open IDE (I used v.23)
3.) Tools >>> Board >> (Duemilanove 2009)
4.) Tools >>> Serial Port (select port your above Arduino is connected to)
5.) File >>> Examples >>> ArduinoISP.. (upload this sketch to your Arduino board.
6.) Disconnect.. from USB
7.) Connect a 100-120 ohm resistor between RESET & +5v (to disable auto-reset on the MAIN board)
8.) Connect your target board (minimal +3.3v/8Mhz internal clock) to the MAIN Arduino above.
Wiring Pnout:
Arduino board pin >>> Target board pin
D10 >>>> RESET
D11 >>>> D11
D12 >>>> D12
D13 >>>> D13
GND >>>> GND
+3.3v >>>> VIN on breadboard...
9.) Reconnect MAIN Arduino board to USB.
10.) Open IDE (I used v.23)
11.) Tools >>> Board >> (Breadboard 3.3v with Internal 8MHz clock)
12.) Tools >>> Serial Port (select port your above Arduino is connected to)
13.) Tools >>> Burn Bootloader >> w/Arduino as ISP
(bootloaded and can upload sketches all day...)..
two things I noticed though...
1.) Does NOT work with Aruino IDE 1.0+ out of the box...not sure exactly how to make it work yet either.
From reading around, it seems to have something to do with:
a.) editing/adding pin_arduino.h or Arduino.h files to somewhere.
b.) edit the breadboard 'boards.txt' file.. and add a line at the end?
(not to sure.. a bit above my comfort level messign with boards.txt and stuff)
this is just specific to my project.. not about the minimal Arduino part..
2.) and the MAIN problem I need to overcome.. I cant seem to communicate/initialize an SD card???
Using an Arduino @ 16MHz (external crystal) & +5v... I have never had a problem.. with voltage divider or level shifter..or shield...
having the Arduino with +3.3v logic and INTENRAL 8MHz clock doesnt seem to work.. and I 'thought' I would be able to directly connect/communicate to it? (no voltage divider, no level shifter..etc)
been searching around.. and havent found much on using 3.3v8MHz internal clock -with- SD card..
anyone done this? (so I know Im not spinning my wheels?)
Lets see the schematic you said you'd post back in #15 & #18, and your sketch.
How'd you bootload it?
(sorry thought I had posted it)..
I ran into this post while searching here on the topic.. and just updated the outcome..
I started a thread about 3.3v/8MHz Internal clock and SD card communication thread here:
I have that circuit mocked-up on a breadboard right now.. before I order PCBs and make it all SMD..
this is the SAME project.. that we discussed via PM.. (ultra tiny pcb with zero space to work with & custom pcb shape/outline)
The last post in the other thread, you say SD PIN >>> Arduino
DAT2(9) >>> NOT USED
CD/CS (1) >>> D10
CMD/DI(2) >>> D11
VSS1/GND(3) >>> GND rail
VDD/V++(4) >>> +3.3v rail
CLK/SCK(5) >>> D12
VSS2/GND(6) >>> GND rail
DAT0/DO(7) >>> D13
DAT1( >>> NOT USED
These are not the correct pins for SPI:
D13 - SCK
D12 - MISO
D11 - MOSI
D10 - SS
What is really connected?
Are you really running from coin cell? May not have enoughcurrent oomph for the SD card.
(not sure if I should post here or there) hahah
hmm.. (Im hoping I just fat finger the pinout!)...
but I thought that was how I had it wired it up:
DAT2(9) >>> NOT USED
CD/CS (1) >>> D10
CMD/DI(2) >>> D11
VSS1/GND(3) >>> GND rail
VDD/V++(4) >>> +3.3v rail
CLK/SCK(5) >>> D12
VSS2/GND(6) >>> GND rail
DAT0/DO(7) >>> D13
DAT1(8) >>> NOT USED
I'll have to check when I get home... looks like I have D12 and D13 switched??
This tutorial has some interesting tips on power saving a minimalist board.
Well I checked it out.. looks like I only typed it wrong..
this is what I have:
DAT2(9) >>> NOT USED
CD/CS (1) >>> D10
CMD/DI(2) >>> D11
VSS1/GND(3) >>> GND rail
VDD/V++(4) >>> +3.3v rail
CLK/SCK(5) >>> D13
VSS2/GND(6) >>> GND rail
DAT0/DO(7) >>> D12
DAT1(8 ) >>> NOT USED
so.. whilke I had typed it with D12 and D13 switched.. checking the wiring.. it was NOT as originally posted..
the above is how it 'is' currently wired.
I can upload any sketch.. but anything that uses the SD card 'fails'..
SD lib >>> Files Sketch:
Initializing SD card...initialization failed!
SdFat lib >>> SdInfo:
SdFat version: 20110902
type any character to start
card.init failed
SD errorCode: 0X1
SD errorData: 0X0
type any character to start
Im not sure where to start troubleshooting?
- Im not sure if this is/could be a boards.txt problem? (a tweak to a fuse setting because the timing is off or something 'odd'?
- Im not sure if I just need to add a cap/resistor somewhere that I missed? (everything is direct connect except for the cap on the VDD/VSS lines of the SD lines)
- Maybe not even possible to do this with 8MHz internal clock @ 3.3v?
Gotta be something silly Im doing on my end..??
heres the schematic:
thanks!
also to answer you Crossroads.
I am using a PSU..
but I have powered/tried it from being powered form the FTDi cable (+5v)..
I have tried from PSU @ +3.3v...
I have 'not' tired the coin cell that I plan on using in the end..(yet).. no point in trying it yet..lol
I am stumped.
Send a pm to fat16lib, ask him to review this thread.
sounds like a plan...
I'll be sad if this isnt even possible.. and Ive been spinning my wheels! lol..
well I PM'd him.. and got a response..
although Im not sure it really applies to me? or if Im over thinking it..etc.etc..
but basically fat16lib responded that SD cards will work with +3.3v/8MHz boards...
he stated he uses one with the Pro-Mini..
and also said he uses this breakout board: SparkFun microSD Transflash Breakout - BOB-00544 - SparkFun Electronics
which to me looks like a 'bare' bones SD socket on a pcb.. (which is good.. since I too have nothing on my SD card)
however.. it looks as if the Pro-Mini 'does' in fact use an external 8Mhz crystal on-board?
and I am using 8MHz INTERNAL clock??..
could this be where the problem lies?
I have changed out the MOSI/MISO/CS/CLK wires too just in case they were 'bad'... still same results..
I wanna hear from ANYBODY that has done this on an internal 8MHz clocked chip?
this is starting to kill my self-esteem! hahaha
thanks guys!
I'm sure that what you are trying to do is possible. It should not matter whether you use a 8MHz crystal or 8MHz internal clock, the SD card does not have an internal time reference so it doesn't care what the exact clock speed is. I suggest:
-
With the SD card removed, run some sketches on your board to test it out. Include sketches that toggle the pins that you use to communicate with the SD card.
-
Check your connections between the mcu and the SD socket carefully, looking for open/short circuits.
hmm..
Im baffled still then...
If the SD card doesnt matter about the clock (external/internal)..
then why isnt it possible? (curious)..
fat16lib says he does it with pro-mini.. +3.3v & external 8Mhz crystal... (stand alone SD socket..no caps/resistors..etc)
so to comment back it 'should' be possible..if others have done it?
I have an LED on pin 13..and that works fine.. I can go through and check the other pins too (12, 11, 10).. to ensure they 'toggle'..(they should..its a brand new chip from the factory)
as far as connections.. its on a breadboard.. and I have replaced the jumpers wires once to check to see if bad connection
thanks!