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31  Products / Arduino Due / Re: has anyone used USART1 as spi sucessfully ? on: May 30, 2013, 08:45:35 am
Oh yes, sorry I was thinking an external protocol. You can't use the DMAC?

for one application yes/ suppose so ..
looks more complicated than the PDC (& which i've used already  ... )
hmmm ...

but fot the other application / I can't because i would like to use the spi for SD card access
(using the USART as a fifo gateway to store data in an external memory)
32  Products / Arduino Due / Re: has anyone used USART1 as spi sucessfully ? on: May 30, 2013, 07:47:46 am

Why does it need a USART, if the USART is in SPI mode what's the difference?

as stated:
the two SPI peripherals can not use PDC, USART(1-4) in spi mode CAN use the PDC

Other chips of the same family spi periphieral can use the PDC ...
 why they don`t on the SAM3x8 .. no idea
33  Using Arduino / Storage / Re: extra RAM on Arduino Due on: May 30, 2013, 04:08:36 am
thoughput oon SPI is great but the latency is killing me...
I'm generating ~30-40megBytes / min  & having the occasional long latency really mucks up my data

I've purchaced a fpga+ram board(ebay) to make a 32Megabyte spi buffer
-- but my verilog/VHDL coding skills are 10years rusty ...   

Also looking at the same fpga SPI buffer to exchange data between the DUE & Raspberry-PI (two masters...) with no droped datas
34  Products / Arduino Due / has anyone used USART1 as spi sucessfully ? on: May 30, 2013, 02:43:03 am
the reason i'm asking is :
i want to use a PDC, which can be used with the USART & not with spi0/1

I'm guessing i have to modify pins in variants.cpp for digital outputs for the strange selection of pins

code so far:
void setup_spi()
    USART_SetTransmitterEnabled(USART1, FALSE);
    USART_DisableIt( USART1, 0xffff) ;
    USART_SetTransmitterEnabled(USART1, TRUE);
    pmc_enable_periph_clk (ID_USART1); 
int spiout (void * buffer, uint32_t bufSize)
return usedSensorWidth;

35  Using Arduino / Sensors / Re: Using a Sony ILX751A Linear CCD with any arduino. on: April 29, 2013, 01:54:48 pm
uhh.. no ...

sample = analogRead(vout); 
blocks on the order of microseconds ... (l00ks like the mega can do 13us if prog correctly default is 100us)
blocks on the order of milliseconds at 9600baud...

 use a scope & trigger a digital i/o to flip hi/lo & you will see your duty cycle ...
    i'll guess .1% dutycycle
36  Community / Exhibition / Gallery / Slitscan Camera on: April 29, 2013, 01:57:07 am

Done & with samples .. small partial schematic(just the sensor) & partial code ( droped the sd card & TFT)
this camera could also be used (modify the software) to run as a finishing line camera
37  Using Arduino / Sensors / Re: Using a Sony ILX751A Linear CCD with any arduino. on: April 29, 2013, 01:22:52 am
datasheet for the ILX751A asks for a clk dutycycle of 40-60%  ..
i don't see that happening with that code ..
38  Products / Arduino Due / Re: SPI across two Arduino DUE's on: April 19, 2013, 03:04:29 am
any luck on slave mode ?

i'm looking to connect a DUE (slave)to a RaspberryPi(master) .. 
and spi has only been implemented on the Pi as master so i figured the Due would be a easier modification ....
 sigh .. time to dig into some data sheets & libs ...
39  Products / Arduino Due / Re: speed of analogRead on: April 03, 2013, 01:45:05 pm
a few comments
the 1Msps is for one channel under very specific conditions
  if you switch channels there is a lag (you will have to look up the details in the data sheet)

IMO best way is to program the PDC with timing generated by the PWM .. with resonable sample code from atmel 
but that will not help you trying to read 80 samples .....

(i'm running at 500,000 samples / sec on one channel, in bursts of ~2k (roughly 4ms/collection ~ pause for 3ms, repeat )

can't comment on the USB , but writing to a SD card "can" be fast  (i'm writing ~500kb/sec),
you need buffer space for sd card lag
40  Using Arduino / Sensors / Re: Using a Sony ILX751A Linear CCD with any arduino. on: March 24, 2013, 03:27:19 pm
these Sony devices have a very simple clocking stucture to follow (as opposed to the National part i was mucking with)

there are really only the 3 steps
pulse low on ROG (once)
pulse on CLK , sample  the data  - repeat 2087 times ....
pause (! found the comment in the data sheet - integreation time is 10ms ! )
and repeat ....
use a scope to check that you have the correct polarities ...

not sure about the MEGA but it appears that you should beable to use the transistor buffer shown in the data sheet so easy to connect ( need clamp diodes for the DUE)
data will look like a stream of 10 bit numbers .... relative to the total amount of light .... 
with junk data at the begining & at the end 
41  Using Arduino / Sensors / Re: Using a Sony ILX751A Linear CCD with any arduino. on: March 23, 2013, 10:21:40 am
follow up :
i've just had 'limited' success in driving the ILX551A ,
very little change programming change from the other chip (upd3799cy)
& i save myself two pins

no data collection as yet but i can see the output change on the scope
whoo hooo !!

it requires VERY little light (i'm up to 200lines per sec ) & still get resonable responce in a medium dark room on a cloudy day ...
& it appears as the native output is close to max 3.5 volts -- so if i clamp it i may beable to feed the arduino direcly (probably have to buffer it but makes life easier ..... )
have to wait till monday  to get sockets , clamping diodes , & assorted other things ... 
42  Using Arduino / Sensors / Re: synthesise a circuit on arduino on: March 20, 2013, 03:38:23 pm
  simple answer - no

 complex answer -
you write a program & run it on a processor
could you "adc", take the root, "dac" it out  ..yes..

will it work like the circuit ... not likely
will it be a synthisised version of a spice deck .. no

43  Products / Arduino Due / Re: Multiple PWM Outputs with Unique Frequencies on: March 20, 2013, 03:13:23 am
Do you know how use that to get higher frequencies like 25MHz?
not possible
must beable to divide 84MHz by an integer so the limits are
42MHz , 28, 21, 16.8, 14, 12, 10.5 , ....
44  Using Arduino / Sensors / Re: Using a Sony ILX751A Linear CCD with any arduino. on: March 18, 2013, 02:06:55 pm
a fast external converter would be possible - not easy but possible
even if you got the data at full speed can you work with it (see below)

you can skip the early parts of the data - either by tossing it out (sampling & over writing) or delay first sampiling  till the ~first valid bits are available

do you have to run at MAX speed?

other things ( at full speed ) to worry about
 MEGA runs at 16 Mhz (62.5ns) this means if you had to run the sensor at full speed (5Mhz / 200ns) you MIGHT beable to fit 3 risc instructions in the time between samples - i haven't looked at the chips instructions but even if you wrote a super tight loop in asm(NOT C/C++) i'm guessing you would need  5-10 cycles (to read /save data / test if done ) no irqs, no timers

(the above is why i'm using a Due)

and a problem that i'm fussing about - do you know (i don't) when is the exposure time for the chip ? it likely needs 1-100ms to collect data (enough photons to make a image) - do these chips double buffer the data (so you have the 1-100ms to pull the data)  or can you only run one line at a time ...

45  Using Arduino / Displays / Re: multiple devices on the 16bit LCD bus on: March 17, 2013, 10:03:31 am
I'd have to use 16 data (+8 for control) should have mentioned TFT not the LCD
have a 7"tft panel on a Due .. (should be plenty of I/Os ..)
& have to do bidirectional 3state level shifts for 16bits
unidirectional level shifts for 8bits
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