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451  Using Arduino / Microcontrollers / Re: Difference between EEPROM and flash memory on: November 09, 2012, 03:59:02 pm
Wow - that's just opened a lot of doors for me, thanks so much for the recommendation. I'll check them out now. This is all a very steep learning curve for me, that is only getting more and more enjoyable smiley-grin

EDIT: I'm just looking at things like data rates - but any preferences of I2C vs SPI? I've only used SPI for ICSP before, and I2C for a few temp sensors. I have chosen SPI as the bandwidth is FAR higher.

On another note, any recommendations for external serial EEPROM chips people have successfully used? Also, what's the bit value talking about here? For example, microchip offer them in 128bit, 1kbit, 2, 4, 8 etc...
452  Using Arduino / Microcontrollers / Re: Difference between EEPROM and flash memory on: November 09, 2012, 03:49:36 pm
I see - thank you for input thus far. I will take a look at port expanding, it doesn't sound like it should be too much of an issue as I only need more general purpose I/O, for things like low rate sensor sampling.

The look up tables are static yes, if they need to be changed - then it's a reflash job, there are slight modifiers to these values, adders and multipliers and what not - but that's temporary stuff that is stored in RAM yes?

Now I know I can up my I/O this way - sticking with the 1284, with it's large amount of RAM - I need not worry about adding external. Maybe just external EEPROM to allow for a bit of future flexibility in the PCB.
453  Using Arduino / Microcontrollers / Re: FT232RL to Atmega UART - is this correct? on: November 09, 2012, 03:33:30 pm
No resistor on the pull up? Is the reset line high impedance in itself then?

That cap, C10, combined with the reset pull up circuit, is the decoupling cap for the power pins yes - not actually anything to do with the reset circuit in itself?
454  Using Arduino / Microcontrollers / Re: Difference between EEPROM and flash memory on: November 09, 2012, 03:11:39 pm
I may jump in here, if I may, as I was about to start a thread asking a question that has come about in the last few replies. I'm working on a project at the moment that will ultimately need multiple large look up tables. 4 or 5 tables of 15 x 10 values for example.

1) Look up tables are stored in EEPROM yes? If so, I can expand the amount of EEPROM I have by adding an external EEPROM chip?

2) Regarding SRAM, if I understand correctly - this type of memory is used up quickly when performing float calculations, doing serial strings etc - can one also expand SRAM with an external chip? Currently I'm using a 1284P, so have quite an abundance of SRAM - however, I/O requirements may see me needing to up to a 2560 chip.
455  Using Arduino / Microcontrollers / Re: FT232RL to Atmega UART - is this correct? on: November 09, 2012, 03:06:03 pm
I see, the datasheet shows no pull up on the reset line to 5V, and the pin descriptor says it is not required - leave unconnected or pulled up to 5V. However - I shall trust your experience.
456  Using Arduino / Microcontrollers / Re: FT232RL to Atmega UART - is this correct? on: November 09, 2012, 10:58:12 am
Quote
Correct. If however you ever have one of the arduino type boards that operates with a Vcc of 3.3vdc then you would connect VCCIO to the 3v3out pin on the FTDI.

Thanks for this - however, this is being embedded in a final design PCB, so will not change. I'll keep that in mind for the future however!
457  Using Arduino / Microcontrollers / FT232RL to Atmega UART - is this correct? on: November 09, 2012, 09:32:11 am
Hi guys,

I'm using an FT232RL to interface to the UART on a 1284P, I'm not using a bootloader so I don't feel I need to use the reset pin from the 232RL to reset the Atmega. The below is my schematic, how I intend to include the 232RL in my design.

1) Looking around, it seems 5V is the correct voltage level for the Atmega UARTS - correct? The datasheet says connect VCCIO to VCC to drive out at 5V TTL.

2) I do not need to use the CTS and RTS pins for handshaking do I? I'm not even sure what handshaking is, the 232RL datasheet just talks about it in it's 232RL to MCU example. Are the RX & TX pins enough by themselves for the chip to talk to the Atmega?

458  Using Arduino / Microcontrollers / Re: Creating pin definitions & boards.txt entries on: November 06, 2012, 06:05:31 am
2. That's one way to do it. I use my MKii to burn a bootloader to set the fuses, and then File:Upload using Programmer to load the sketch.  Mostly because I don't like waiting around for Atmel Studio start up.

Many thanks again - that's how I successfully did my 1284P-PUs, I just thought that a different signature would mean different bootloader, but now I know it's all the same.

Cheers!
459  Using Arduino / General Electronics / Re: AC current on: November 04, 2012, 10:27:10 am
Building your own H bridges is great to learn about them, but in an application if space is an issue - you're probably better off using an H bridge IC such as the LMD18200 or L298 as these have features such as overcurrent / overtemp protection, seperate enable functions, internal clamp diodes etc.
460  Using Arduino / Microcontrollers / Re: AC lamps dimmer circuit on: November 04, 2012, 10:23:04 am
A post like this should be located in the Project Guidance section, as you are looking at a concept at the moment. However, you probably won't find much help from people unless you post specific problems, and ask specific questions.

I'm assuming you're talking about mains power here? Do you have experience working with deadly voltages, as I'm not sure people would be willing to give somebody drawings to wire up voltages that can kill.
 
Have you actually got the 8535 working yet? I guess you're not using a bootloader.
461  Using Arduino / Microcontrollers / Re: Creating pin definitions & boards.txt entries on: November 04, 2012, 08:59:57 am
Does the device signature not change then between package type?
462  Using Arduino / Microcontrollers / Creating pin definitions & boards.txt entries on: November 03, 2012, 02:09:04 pm
Hi all,

I've been working on a design using an Atmega1284P-PU in the DIP package, however due to space constraints may have to switch to the 1284P-AU in the TQFN package.

Now, I'm not using a bootloader - I am simply flashing with an AVR ISP Mk II over ICSP.  I will still have USB communications available for serial debugging and SD storage download, however that is another story. How would I go about using the P-AU version with the Ardunio IDE?

1) I'm assuming i'll need to make another entry in boards.txt as the device signature will be different.
2) Regarding fuses and lockbits etc, I'll set these with Atmel Studio - so all the trouble people have been having with bootloaders, is not a problem here.
3) Setting pin definitions, again - i'm assuming another file will be needed somewhere here? Here is where I'm a little lost.
463  Using Arduino / Storage / Re: SD contents download via USB on: November 02, 2012, 07:46:35 am
So in theory, I could simply send a 1 to the controller by serial, and it would return all of the stored values, one by one so to speak? ...and careful serial prints with the commas in the correct place, would in some way or another - create a serial stream I could paste into notepad to create a .csv file?

In terms of how much data, 5 or so channels logged at 1Hz, another 4 or 5 logged at about 15Hz, in periods of roughly 30 minutes.
464  Using Arduino / Microcontrollers / Re: Standalone USB communications on: November 02, 2012, 05:33:10 am
I wasn't trying to put you down, please don't take it that way.

Nono, I didn't take it in that way at all - do not worry!

I'll try the suggestions, many thanks.
465  Using Arduino / Storage / SD contents download via USB on: November 01, 2012, 04:25:54 pm
I haven't started playing with SD card logging yet - however, a project I'm working on has a requirement for datalogging. I would like to be able to download the logged data (preferably as a .csv file) to a PC via USB - is this possible?

...and as I plan to download this data via USB, and not actually remove the SD card - is SD even the way to go about it - what other storage medium could I use?

Just trying to feel the water here - so to speak.
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