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31  Products / Arduino Due / Re: How to connect a 5v TTL board to Due on: February 10, 2013, 12:52:36 pm
Well, I think there is no general answer. Even in this specific case, it depends on what drivers the SSC-32 has. I suspect you know more about that than we do, but you haven't told us what chip it uses; looking at it's schematic is the only way to find out what will work. An answer also depends on what switching rate, how many channels, is it bidirectional, open drain, TTL/CMOS, TH/SMT etc. Just too many unknowns which only you can decide.

There are dozens of ICs available depending on requirements, I would try to use one of those, particularly if unidirectional.

I think you are aware of the possible solutions, but only you can decide what is best for your application.
32  Products / Arduino Due / Re: How to connect a 5v TTL board to Due on: February 10, 2013, 07:54:42 am
I am sorry if this has been answered before, but my searches are not showing up any thing...

I would like to connect one of the USARTS of the DUE to an SSC-32 (servo driver board), whose TTL is at 5v.

What is the preferred way to connect them.  I figure the TX is fine as the SSC-32 will probably handle the lower voltage just fine.  But about the RX where the SSC-32 may return data.

Limiting Resistor? if so how big

Resister Divider?


If you are planning to connect to the DB9 connector you need to handle voltages -12 to +12. TX might possible work at 3.3V, but it is pretty borderline. I would use something like MAX3223 to provide proper translation levels.
33  Products / Arduino Due / Re: Arduino Due: 16-bit int and others data types on: February 07, 2013, 05:35:48 pm
I would encourage you to use stdint.h. This has types such as uint16_t, int16_t etc if you need to be explicit about bit widths.
34  Products / Arduino Due / Re: Due I2C not working on: February 06, 2013, 08:05:07 pm
What speed are you running the I2C at? I imagine that with different pullups and level translators there could be a lot of skew on the edges.

ETA: this link suggest that the SFR02 uses a PIC micro with VIH = 4V, so a pullup to 3.3V seem to be insufficient. In that case though, I can't see how it works at all, unless there is a lot of tolerance on that 4V level.

I'm keen to find out if level translation on I2C is practical, or whether I need to spec peripherals to be 3.3V only. Unfortunately I haven't the kit to play with at the moment.
35  Products / Arduino Due / Re: Arduino 2 and printer 3d on: February 04, 2013, 03:39:23 pm

I am currently working on adapting the RAMPS printer control shield for Due. Soon I hope to start porting some RepRap firmware to the Due also. There is a web page describing the concept.

I'm currently working on porting Reprap firmware to an NXP ARM chip (LPC1114). Hopefully I will be able to make a multiplatform firmware to run on AVR, SAM3X or LPC11xx, possibly others, using ChibiOS. I've already done a Reprap firmware for STM32 using ChibiOS.
36  Products / Arduino Due / Re: Due EEPROM alternative? SD? on: February 01, 2013, 10:49:38 am
So the DUE does not have internal EEPROM at all?

No, only Flash.
37  Products / Arduino Due / Re: Wireless SD Shield usable? on: January 29, 2013, 06:15:04 pm
Please note that the Wireless SD Shield is NOT the same thing as the WiFi Shield!
38  Products / Arduino Due / Re: connecting the Due board to a WiFi shield on: January 27, 2013, 10:35:15 am
Hi cmaglie,
thank you for your response.

*just to be clear, I am talking about the Arduino Due.
not about the Arduino Duemilanove (which was replaced by the Uno)*

At the WiFi Shield's description ( ) it's specified that "...It is compatible with the Arduino Uno and Mega." but there is no mention of the Due or any other board, so I've figured...

You are right, the description of the shield does not indicate it is compatible with Due/3.3V, but in fact it is. It has a level translator already for 5V/3.3V signals.

In addition, the operating voltage of the shield is 5v and the Due supplies only 3.3v (which I believe can be fixed by transistors but still need to be considered).

here you are confusing several things, to clarify:
1) the Due supplies both 3.3V and 5V power
2) a shield can be *powered from* 5V but still be compatible with 3.3V baseboard (or vice versa)
3) it is the IO signals that require level translation, this does not relate to power supplies

In short, the wi-fi sheld will work fine with the Due, do not worry!

39  Products / Arduino Due / Re: Due Interrupt Bug on: January 27, 2013, 09:51:10 am
"Interrupt on change" is a deceptive feature, it makes it look like sampling digital inputs is quick and simple. In general, you must debounce all signals coming into the CPU, this applies particularly if you are sampling a mechanical switch. Even many solid state devices can generate a slow rise time signal, and with a small amount of noise which tends to be always present in digital circuits, can trigger multiple times around the logic high threshold.

The "interrupt on change" really means "something is happening". That something could be a spurious glitch due to noise, or it could be real a change of state. To tell the difference, one method is to start a timer when the signal changes. A short time, say 10ms, after the signal has stopped changing, test if the new state is different to the old state. Only then act on the new state if it has changed.
40  Products / Arduino Due / Re: Arduino DUE and SPI 9 bits on: January 25, 2013, 04:47:11 pm
I want use the functionality of the arduino DUE to send 9 bits SPI data.

I havn't found anything in your SPI documentation about the SPI data length..

Any hint for me?

The SPI peripheral in the SAM3X can do 9 bit transfers, but this is not supported by the SPI library. It would be very easy to add though.
41  Products / Arduino Due / Re: Maximum Pin Usage on Due (any duplicate/dedicated pins?) on: January 25, 2013, 02:55:19 pm
I am looking at the file ...\arduino-1.5.1r2\hardware\arduino\sam\variants\arduino_due_x\variant.h. This has BOARD_SPI_SS3. On the Due schematic, SS3 is pin 142, PB23, but is not connected to anything.

If you are desperate for IO, there are 4/5 pins on the JTAG connector that could be used.

If you are *really* desperate for IO, there are several unconnected pins. With some fine wire, decent soldering skills, and good seeing, you could bring them out to an external header.... perhaps not a very robust solution, but a dab of glue could help.
42  Products / Arduino Due / Re: Maximum Pin Usage on Due (any duplicate/dedicated pins?) on: January 25, 2013, 01:39:02 pm
The dedicated SPI is just SPI, I think, there is only one SPI supported by the Due SPI library. The Due pins are numbered D74,D75 and D76 and these are the pins used by SPI lib.

I'm not sure about the SPI-CSx pins, are they used in Master or Slave mode? SPI-CS3 is not mapped anywhere (unconnected on SAM3X), so if you don't want SS/CS then specifying BOARD_SPI_SS3 will ensure the SPI does not interfere with other pins.
43  Products / Arduino Due / Re: Maximum Pin Usage on Due (any duplicate/dedicated pins?) on: January 25, 2013, 11:51:02 am
I would like to use the most pins possible on my Due.  I have read in a few places that some pins are duplicates?

I cannot read a pin schematic and make heads or tales of it.  It says that D10 = D77 and D4 = D87... are those duplicates in the CODE, or on the physical board?

They are physically shared signals on the board. I think they are the only two lines shared in this way. All the other lines are mapped 1:1 with pins on the the SAM3X.

Followup:  What about if I (additionally) use the dedicated SPI pins in the middle (for SPI)?  What pins are those duplicates of?

You can use MISO, MOSI and SCLK on that connector, and they are not physically shared with other pins.

That is how I read the schematic, I am sure if I am wrong someone will correct me smiley
44  Products / Arduino Due / Re: Connecting an Ethernet PHY to Arduino Due on: January 25, 2013, 10:59:20 am
Do you think we could use this cheap Enc28j60 boards, which are on ebay for 4$ instead of using AS-DM9161?

For connection to SAM3X8E ethernet pins I would go with pogo-pins mounted on the bottom of DIY shield for DUE.

The ENC28J60 is an SPI connected MAC/PHY chip. It would work, if you have a driver for it, but would be a lot slower than a PHY connected to the ETH  interface on the SAM3X. If you are doing occasional requests like HTTP, it would probably be OK, if you want to transfer a lot of data I think it would be lacking performance.

It is a cheap and relatively simple way to add Ethernet though.
45  Products / Arduino Due / Re: Minimum schematic design for arduino due on: January 24, 2013, 04:24:32 pm
What about crystals and such? I only see a 32khz and 12Mhz oscillator. Where is the 90Mhz 1?

I am intending to use the acr isp mkii to program the microcontroller. As such i would like to know all necessary connections i have to connect in order for that to work.

Based on given schematic, i figured i have to at least connect the crystals, the vdd, the gnds, miso, sck, mosi, master reset etc.

Did i miss anything important?

Well, if you want the *bare* minimum, to just flash an LED, you can use the internal RC oscillator. If you don't want to go fiddling with startup code, then you better fit the 12MHz crystal. the 32kHz crystal is used for the real time clock, you can decide whether you need that or not.

AVR specific tools will not work with Atmel SAM series, they are completely different architecture. If you just want to program the chip, you can use the builtin bootloader and the SAM-BA programming software from Atmel.
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