May 23, 2010
about a month ago
Well, I feel stupid! Always read the specifications!
So the shift is required then? If so, that means the TWI library and software libraries I’ve used have a bug in them.
about 2 months ago
Thanks! I don’t have any tools, so I would never have been able to figure that out. That logic analyzer isn’t that expensive. I need to start collecting tools.
Where does this shift occur and is it part of the i2c specifications? That cannot be right.
I just said screw it and went with UART. It just wasn’t worth the headache and I cannot find a way to remove the bootloader. Oh, sure… Google gives plenty of sites that state it can be removed, but I have yet to find one that details how! O.o I’m not going to risk bricking the AVR since I can get it to function with the UART. Again, not worth the headache.
Still, it doesn’t work as advertised and that’s a problem that Sparkfun needs to address. Promptly.
Unfortunately, no luck on this display either. I can confirm that my ATmega32 is working, but so far I cannot get this or the smaller display to work with the i2c bus. I’ve tried both the hardware TWI interface and software libraries across two different chips. This makes me think that this is an issue with the Arduino Wire library. I’m curious if anyone has gotten these displays to work with i2c using straight AVR C/C++. The display is just an Atmel microcontroller masquerading as an i2c device through the Arduino Wire library. That has to be the issue. I would imagine it would work if I were using Arudino, and it appears that they tested the i2c interface with an Arduino, but wonder if it was tested with an AVR without Arduino? This would be a necessary test as not everyone uses Arduino.
I’m not sure if it is possible, but I am tempted to flash over the Arduino bootloader with a custom C/C++ firmware taking advantage of the AVR’s hardware UART, SPI and i2c buses. I don’t trust libraries in cases like this. Too many potential issues, especially since the libraries are a software abstraction layer over hardware functionality. Who knows what is going on behind the scenes.
Unfortunately, they are focused on providing Arduino examples. While I appreciate how Arduino has made microcontrollers accessible to the masses, the oversimplification has started to creep into the worst of places, like the documentation. I would almost be willing to pay extra if they would write a straight AVR C/C++ based firmware, along with examples and documentation.
To answer your questions, you send the 7-bit address, 0x71, plus the R/W bit, with the i2c start command and then send the byte commands shown under the basic serial documentation. Pull ups are required, regardless of what the documentation states. 4.7K on both pins.
The best thing to do is to download the firmware and study it. It will shed partial light on what is going on behind the scenes.
I should mention that I couldn’t get the smaller 7-Segment Serial Display to work with i2c at all, to the point of having to request a refund. I should get this display as a replacement in the mail on Monday and I’m hoping to have better luck. They use the same firmware, but I am being cautiously optimistic.
about 2 months ago
Hey… The GitHub data sheet is cool and all, but a downloadable PDF would be nice as well… :/
News - LilyPad MP3 Giveaway!
about 7 months ago
I work in a manufacturing facility and we are required to wear ear protection. We have the choice of ear plugs or ear muffs, and I would like to modify the ear muffs to include a hidden (more or less) MP3 player. The LillyPad, speakers and battery should fit easily in the ear muffs.
about 9 months ago
Is there any form of instructions available? I can’t find any online and was hoping that there would be something with the programmer, but no. :/
about 10 months ago
So, I got it modded. The segments are removable. Each segment has four pins, although I am unclear on the spacing. I superglued the segments together, traced and cut out the digit in black foam board and hot glued it in place. I was wiring it up as a common cathode when I realized I was out of solder…
No public wish lists :(
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