Saturday, May 19, 2012

SDHC USB Bootloader and Logging Firmware work!

I have the old Logomatic 2.3 working with the new SDHC USB bootloader. At first, FAT32 was not enabled. because the mass storage part doesn't even need a filesystem driver, the host takes care of it. However, In order to find and install FW.SFE, the bootloader needs FAT32 however, so this version has it.

Also, the old Logomatic firmware has been updated the minimum amount to use SDHC and FAT32.

All of this works for me, and generates log files, but it sometimes takes a LONG time to mount over USB (sometimes a minute or more).

So now I have put my code where my mouth is.

Friday, May 18, 2012

More on SDHC

So here's the problem. There are in fact two SD card drivers in the Logomatic firmware. Hey, by the engineering method, anything that works is good, and the Logomatic code works, but it's not great code. There are entire sections that are included but not used, like the USB driver in the main logging firmware. Now we have two pieces of code to do the same thing -- access the SD card. There is Roland Riegel's code used by rootdir.c and used by both the bootloader and main code to read and write the card, and there is the code used by the USB driver, which is entirely separate and entirely unready to do SDHC.

So, I am going to update the USB driver to use Roland's code. This just means mapping what the code is doing now to the various parts of sd_raw.c . Piece of cake, probably. We'll see.

Anyway, once this is done, I'll post a message about it on the Sparkfun forums, direct them here, and get literally some readers on this blog, rather than just myself like I get now.

No bragging until I can put my code where my mouth is.

By the way: I am doing all of this development on the Loginator 1.1, so the SD card slot and USB port work. Yay for me!

The LPC1768

It's sooooo close to being awesome. Cortex M3 with all the improvements (don't be scared by the word Harvard, the program-visible memory map is flat) and full pin compatibility with the 2368.


This part has no SD/MMC port. Still, with SPI and DMA, maybe we don't need SD/MMC. The part is otherwise pin-compatible with the 2368, so the 2368 breakout board should work with a 1768 also.

I am going to get a 2368 talking to an SD card and sensor before I try messing around with the 1768.

Loginator2148 v1.1 is assembled

I have every confidence that the board is correct. I have tested that the known bugs in the old board have been eradicated. I have every confidence that the parts are properly placed and that all joints are good. I have tested the power supply, charge circuit, and lights.

So why am I not more confident in this board?

Is it live...

...or is it Memorex?
All of the switches and the battery terminal were partially melted/burned with hot air. The power switch is especially bad. Everything seems to work, though. It's just ugly. Next time, we bake the plastic parts. Maybe we bake everything. Maybe we salvage this board by lifting all the burned parts, replacing them, and baking it. Maybe we just don't make this board again. I would kinda like to get out of the 2148 business and into the 2368 business.

Update: The thing is alive, the Arduino terminal just doesn't know how to talk to it. I sent ? and saw 'Synchronized' on the logic analyzer (great device, I'll write a review some day). It just didn't show up in the serial terminal. This means that the controller is alive enough to communicate over serial, which means that the crystal and decoupling caps are on and the power is properly hooked up. The thing was running on battery when I tested this, so the whole battery part works too. Wow, I guess a lot is tested just with "Synchronized".

I wish these pictures showed the glorious royal purple and gold of the boards.
This is a NON-FLIGHT configuration. Not that the Loginator is ever intended to fly, anyway. This is just so that I can learn how to talk to the sensors and get the IMUinator working

Wednesday, May 16, 2012

11DoF is working

I finally put together an 11DoF. All sensors are on board, but I decided to forgo the OR gates until I see that I need them. That means that both solder bridges on the back are closed, and the board is subject to Analog silliness if it decides to show its head.

Here we have the design...

And here is the physical implementation. Is reality ever as clean as design?

All of these sensors work, in that the I2C compass and baro/temp sensor actually work, and the SPI accel and gyro respond to SPI commands and return their proper chip IDs. I haven't tested full functionality on those guys yet.

So, do I start making and selling these things for $50 each? Or do I just release the design and say "have at it" yourself?

If the latter, here are the files:

11DoF Schematic (Eagle 6.x)
11DoF Board

Next version? There's always a next version. Both STMicro (makers of the L3G4200D) and Invensense (makers of the ITG3200 that I gave a glowing review to) have 6DoF sensors, and one of them even makes a 9DoF sensor with a magnetometer in the same chip as the accelerometer and gyro. The problem is that these parts are not yet available from Digikey, and therefore not really available at all. Also, the interfaces are ugly: Both parts have two SPI interfaces. The Invensense part has one for the gyro and one for the accelerometer, while the STMicro part has one for the gyro and one for the acc/compass. It is almost as if two devices are just crammed into the same case. I can cram together parts, in fact that's what the 11DoF board is. I want a 6/9DoF part to have a single SPI interface with a single chip select, and perhaps more importantly, I want the acc and gyro to sample at the same time and have one interrupt line.

Wednesday, May 9, 2012

Designing a large charlieplex

I saw a new cool way to design a charlieplex, one which is easy and obvious, even for an extremely large LED matrix. This was buried in a post below where I blather on about my own problems, so I broke it out into a post that Google is more likely to find.

Monday, May 7, 2012

Details Matter...

...and they seem to cost about $50 each.

The boards for Precision 1.1 arrived on Saturday, part of an ocean of purple boards. I had previously ordered all the electronics for it, so I was all ready to assemble it, except...

  1. In Eagle, I copied the crystal from some other source, and it was still labelled 12MHz like it was from some LPC2148 board. Before, I had manually ordered parts, but this time I used add-digikey.ulp, which dutifully noted that the part was 12MHz and the same case as the Logomatic crystals, so it ordered a 12MHz crystal and I missed it.
  2. I had decided to use 91Ω resistors to try to solve the "extra lights" problem, but after having the clock set up, I decided that brightness was more important than extra lights, so I decided back to use 47Ω resistors like with Precision 1.0
This wasn't that much of a problem, as I had a complete but unusable board from a previous forgotten detail, so I could lift the 47Ω packs and 16MHz crystal from it, without ruining the working front board I already had. This avoids the "one brief shining moment" problem, when you have something that kinda works, but you want to improve it and destroy it in the process. I still have a working Precision 1.0 front board.

Now for today's $50 detail. The primary features of Precision 1.1 are the green wire fixes from last time and a port for the UP501 GPS unit in place of the EM406 port from 1.0. Well, I was planning on using the back board from Precision 1.0 as-is, since it already has $50 of blue and green lights on it. However, it has the old GPS port on it, with certain pins grounded and certain pins connected to VCC - the wrong pins, as it turns out. One of the new 3.3V pins matches one of the old VCC pins, so there is a direct 1.7V short, which I'm surprised didn't completely burn out the FT232. Maybe it did partially burn it out, but there is no way to check right now. The new PPS pin is grounded on the old board, in a flood of polygon that is impossible to isolate. Even though the back board has no electronics on it, it still interferes. This is the $50 detail. Now I have to order a new set of lights. Or... I can lift the lights off of the old board, but that would create a brief shining moment problem. So, it will be new lights.