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16  Using Arduino / Storage / Re: RamDisk - a file system library for RAM devices like 23LCV1024 on: April 01, 2014, 04:45:49 pm
Performance (5MB bench test) of the 8MB ramdisk with RamDisk file system - buffer size vs. rd/wr speed vs. "latency - buffer copy time".
Below picture with atmega1284p @16MHz and bitbanging (slow). Will be much better with DUE and its External Memory Bus (8bit static device) - I would guess 11-12MB/sec with DUE is feasible.
17  Using Arduino / Audio / Re: Best anti-aliasing filter to use for sampling audio on arduino? on: March 31, 2014, 05:13:40 pm
Long time back I messed a lot with active filters - it is not as easy as it seems, as you need quite precise components to build something useful. The easiest way is the MAX or something else of that kind. Mind when messing with arduino's ADC the effort with high-quality analog AA filters is not appropriate, afaik.

"The MAX7400/MAX7404 provide 82dB of stopband rejection and a sharp rolloff with a transition ratio of 1.5. The MAX7403/MAX7407 provide a sharper rolloff with a transition ratio of 1.2, while still delivering 60dB of stop band rejection."
18  Using Arduino / Audio / Re: Connecting arduino to speaker using 2n3904 npn transistor on: March 31, 2014, 05:02:28 pm
Quote
Hello I am studying electronics
Did you search for "speaker transistor" etc. in this forum?? Study means research..
http://forum.arduino.cc/index.php?topic=171105.0
19  Using Arduino / Audio / Re: Best anti-aliasing filter to use for sampling audio on arduino? on: March 31, 2014, 04:48:41 pm
MAX740x - 8th order filters, 8pin, tuning (1Hz-10kHz cutoff) with 1 capacitor wired from Clock input to gnd. Works fine.
http://www.maximintegrated.com/datasheet/index.mvp/id/1899
20  Topics / Science and Measurement / Re: Pulse generator? on: March 31, 2014, 04:23:59 pm
http://www.avr-tutorials.com/assembly/calculating-execution-time-code-single-loop
http://www.avr-tutorials.com/assembly/calculating-execution-time-code-double-loop

AVR delay calculator:
http://electronics-lab.com/downloads/mcu/003/index.html

Quote
first output generates 10 usec pulse with frequency 10 Hz.

1. loop start: pin high
2. 158 cycles
Code:
; =============================
;    delay loop generator
;     158 cycles:
; -----------------------------
; delaying 156 cycles:
          ldi  R17, $34
WGLOOP0:  dec  R17
          brne WGLOOP0
; -----------------------------
; delaying 2 cycles:
          nop
          nop
; =============================
3. pin low (160cycles = 10usec)
4. 100ms period - we need (1.600.000 - 160) cycles (maybe minus 1 or 2 because of the loop)
Code:
; =============================
;    delay loop generator
;     1599840 cycles:
; -----------------------------
; delaying 1599831 cycles:
          ldi  R17, $1B
WGLOOP0:  ldi  R18, $4F
WGLOOP1:  ldi  R19, $F9
WGLOOP2:  dec  R19
          brne WGLOOP2
          dec  R18
          brne WGLOOP1
          dec  R17
          brne WGLOOP0
; -----------------------------
; delaying 9 cycles:
          ldi  R17, $03
WGLOOP3:  dec  R17
          brne WGLOOP3
; =============================
5. loop end

Not tested, just calculated  smiley  smiley



21  Using Arduino / Storage / Re: RamDisk - a file system library for RAM devices like 23LCV1024 on: March 30, 2014, 02:13:40 pm
FYI (digikey, rlx):
Small comparison of "serial" SPI SRAM/FRAM/MRAM prices (single quantity and per MByte).


22  Using Arduino / Storage / Re: More memory to save data on: March 30, 2014, 01:47:38 pm
You have to define the data rate you are assuming with your design. You say 4 sensors, floating point, 1000Hz sampling rate and 10seconds. That may leed to 16kB/sec or 50kB/sec based on the format stored.
I personally would go with MRAM (512kBytes per chip, 8pin, SPI) nonvolatile and w/ the above fat16lib's filesystem when talking 10sec recording at the guessed data rates above. For more demanding application you may consider the 8MB ramdisk.
23  Development / Other Hardware Development / Re: 8MB Ramdisk (external RAM) for Arduino.. on: March 30, 2014, 01:17:13 pm
Enclosed plz find the version 0.9 of the 8MB Ramdisk driver for the fat16lib's latest "RamDisk File System".
P.
24  Using Arduino / General Electronics / Re: Help me understand what's going on with the reset circuit in this simulation. on: March 30, 2014, 05:31:56 am
The basic way how to discuss electronics is with a schematics (pictures), simulation results (pictures, numbers), placed here in this post within this discussion. You can easily refer to components, voltages, currents etc then.
You can hardly discuss an animation somewhere out of this thread. People who understand electronics do not need to mess with animated java stuff somewhere in the cloud in order to help you. They need to see a concrete schematics you are referring to (a picture) and simulation results (a picture) when necessary. And they may help you then.
25  Using Arduino / General Electronics / Re: Help me understand what's going on with the reset circuit in this simulation. on: March 30, 2014, 04:57:43 am
Show/post your schematics or simulation pictures here. Do not post links to java applets. So you can discuss the stuff in detail.
26  Using Arduino / General Electronics / Re: potting? silicone? epoxy coating? specifics on weather proofing Arduino circuit on: March 30, 2014, 04:26:52 am
When you talking people with experience they tell you the only way how to make electronics in a box weather/moisture proof is to drill a small hole (ie 3mm dia) into the box (at the very bottom side, of course). Everything else does not work in real life smiley
27  Using Arduino / Storage / Re: RamDisk - a file system library for RAM devices like 23LCV1024 on: March 30, 2014, 03:48:21 am
FYI - this RamDisk filesystem could work nicely with serial SPI FRAM (ie. FM25V10, 256kBytes per chip, 8pin) or serial SPI MRAM (ie. MR25H40, 512kBytes per chip, 8pin) where FRAM and MRAM are nonvolatile.
The performance will be exactly the same as the one with above serial 23LCV1024 SRAM, the driver is basically the same (small change required probably in the addressing sequence).
28  Using Arduino / Storage / Re: Storage Space on a device on: March 30, 2014, 03:37:30 am
For storing 80kB or similar small amounts you may use external serial SPI EEPROM/FLASH (slow writing speeds, not critical for your application), or fast devices - SPI SRAM (ie. 23LCV1024 128kBytes, 8pin, needs backup battery) or serial SPI FRAM (ie. FM25V10, 256kBytes per chip, 8pin) or serial SPI MRAM (ie. MR25H40, 512kBytes per chip, 8pin) where FRAM and MRAM are nonvolatile.
See for example the newest from fat16lib http://forum.arduino.cc/index.php?topic=229485.0 - you can even have the filesystem on the device today and it works.
29  Using Arduino / Storage / Re: RamDisk - a file system library for RAM devices like 23LCV1024 on: March 29, 2014, 07:54:37 pm
A quick hack of sdfat's bench sketch - bench_8MB.ino:
Code:
Type any character to start
Free RAM: 15761
File size 5MB
Buffer size 100 bytes
Starting write test.  Please wait up to a minute
Write 745.60 KB/sec
Maximum latency: 212 usec, Minimum Latency: 112 usec, Avg Latency: 129 usec

Starting read test.  Please wait up to a minute
Read 745.41 KB/sec
Maximum latency: 172 usec, Minimum Latency: 120 usec, Avg Latency: 128 usec

Done
Not sure how to interpret the latencies here as they depend on the buffer size..  smiley-confuse
Code:
Type any character to start
Free RAM: 11861
File size 5MB
Buffer size 4000 bytes
Starting write test.  Please wait up to a minute
Write 1029.44 KB/sec
Maximum latency: 4120 usec, Minimum Latency: 3816 usec, Avg Latency: 3880 usec

Starting read test.  Please wait up to a minute
Read 992.26 KB/sec
Maximum latency: 4288 usec, Minimum Latency: 3996 usec, Avg Latency: 4025 usec

Done
It seems those are the times for copying to/from buffer, or something like that..
30  Using Arduino / Storage / Re: RamDisk - a file system library for RAM devices like 23LCV1024 on: March 29, 2014, 04:51:54 pm
RamDiskToSdFat_8MB.ino:
Code:
FreeRam: 15256
Format (Y/N): Y
Writing ramFile
TEST.CSV      2000-01-01 01:00:00 16664
Copying ramFile to sdFile
TEST.CSV       2000-01-01 01:00:00 16664
Done

Test.csv from the sdcard:
Code:
0,Line,0
336,Line,1
728,Line,2
1128,Line,3
1536,Line,4
..
567696,Line,996
568280,Line,997
568860,Line,998
569444,Line,999
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