Sections for avr-objcopy

When you compile an AVR C program, you get object code, which you have to convert into HEX format to flash onto the chip.  You do this using avr-objcopy, and there are apparently several valid ways of doing it.  I recommend learning about what the -j and -R flags are doing when you come across tutorials with this command in them.  I was using one from a tutorial that looked like this:

avr-objcopy -j .text -O ihex some.o some.hex

That’s all fine and dandy except it only works for programs that don’t end up using the .data section of the object code! Now, this wouldn’t be a big deal if there were any warnings about this, but there aren’t – you just have to know to add a -j .data. A better solution, posted here by clawson, is to use the -R flag to remove parts you know you do not want. Here’s my current strategy:

avr-objcopy -R .fuse -R .lock -R .eeprom some.o some.hex

This fixed 2 separate problems when I did it, one with struct initialization and one with my LCD displaying block characters for strings but working for single characters.

LCDiesel on Github

Here’s a quick code example using the library:

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "lcd.h"

// Include the chars we want
#define CHAR_USE_OPEN_RECTANGLE
#define CHAR_USE_HEART
#include "chars.h"

int main(void)
{
    /* initialize display, cursor off */
    lcd_init(LCD_DISP_ON);
    lcd_command(LCD_FUNCTION_4BIT_2LINES );
    lcd_clrscr();

    // Testing if x,y are set wrong
    lcd_gotoxy(3, 1);

    // Load character
    lcd_custom_char_p(0x00, _char_open_rectangle);
    lcd_custom_char_p(0x01, _char_heart);

    // We better still be at 3, 1
    lcd_putc(0);
    lcd_putc(1);
    lcd_putc(255);

    for(;;);
}

See how easy it is to define custom characters? Cool, huh? I think so. The heart and rectangle bit vectors are in chars.h, and are only compiled in when they are defined, keeping code size down. Here’s how I have it hooked up on the breadboard (and the output of the program above):

Also, I discovered that MAKE: Electronics is an awesome book. I highly recommend purchasing yourself a copy.

Overall, this is great for the intermediate electronics nerd who wants to take a circuit from board layout in Eagle to working semi-professional product! I had a lot of fun doing it, and making small modifications will be even more fun.

This is for the MintyBoost XL, which is totally awesome. Now I just have to etch it, drill it, and solder all these little components onto it…

I used the instructions found here to create this little gem. They are very good, but I modified the method slightly. Instead of taping crap down, you just heat up the board like he says, carefully stick the paper to it toner side down, and start ironing for a few minutes, pushing hard and using the tip of the iron to go over every everything nice and hard. Also, cleaning is key – I used some 220 grit sandpaper and then acetone with a paper towel, and it turned out great.

The schematic is available here. All credit really goes to Robert Hunt though – it’s his design. Also, here’s my slightly modified parts list I ordered from Digikey for this project:

1 811-2042-ND INDUCTOR RADIAL 22UH 2A
1 LT1303CN8-5#PBF-ND IC DC/DC CONV STEP-UP 5V 8-DIP
1 3M5473-ND SOCKET IC OPEN FRAME 8POS .3"
2 CF14JT100KCT-ND RES 100K OHM 1/4W 5% CARBON FILM
1 1N5817DICT-ND DIODE SCHOTTKY 20V 1A DO-41
2 BC22AAW-ND HOLDER BATT 2-AA CELLS WIRE LDS
2 490-5401-ND CAP CER 0.1UF 50V Y5V RAD
2 P5112-ND CAP 220UF 6.3V ALUM LYTIC RADIAL
1 UE27AC54100-ND CONN RCPT USB TYPE A R/A GOLD

Total parts cost: $11.87.

Not too bad for a little DIY and fun. Board cost a few pennies.

UPDATE

I got tired of waiting for my FeCl in the mail, so I used some awesome instructions to take Muriatic Acid (also known as Hydrochloric Acid) from Lowes and Hyrdrogen Peroxide and mix ‘em together with the PCB to etch it, and also yield a byproduct of Cupric Chloride, which is also a reusable etchant itself! And it did a fantastic job:

I made sure to find plastic containers that don’t react or melt when exposed to the acid – my tray was from Walmart and is PVC and my container for the leftover acid was an HDPE milk jug. So far, so good!

I downloaded version 2.80 of the firmware from here.  I’ve also posted it here just in case.  I found some instructions here to upgrade the firmware, and I’ve reposted them here for posterity:

How to Download the Upgraded Firmware

Make sure the power supply is fully secured during the whole process of Firmware Upgrade. We recommend to use as fully charged batteries and AC Power Supply together for un-interrupted power supply during the Firmware Upgrade.

1. Download and save the firmware to your hard-drive. Unzip it to find the .HEX file.
2. Make an Upgrade CD by burning iMP-350.hex onto a blank disc.
3. Connect iMP-350 to AC adapter.
4. Insert Upgrade CD into iMP-350.
5. Press Play Button to permit Power Supply to iMP-350. LCD display will show the iRiver Logo and Loading during the course of firmware upgrading. Blinking display is normal during upgrading. *DO NOT TURN THE MACHINE OFF DURING UPGRADE* *IF NEEDED CHARGE BATTERIES FULLY BEFORE UPGRADE SO THE MACHINE WILL NOT TURN OFF DURING UPGRADE*
6. After completion, power will shut down automatically.
7. Remove Upgrade CD from iMP-350.
8. Insert a music CD and turn it back on.

Conclusion

Overall, it’s a really great player.  I think I’m going to enjoy using it thoroughly!

Projecting the Impact of a Geomagnetic “Superstorm”
Posted: Jan 23, 2009

As the sun begins to rouse from its prolonged quiet period at the bottom of the sunspot cycle, hams around the world are looking forward to the next solar peak and the big band openings on HF and VHF that will accompany it. But a big solar peak can also result in big solar flares, followed by big geomagnetic storms here on Earth. And that has some researchers working for the National Academy of Sciences very worried. Their report, funded by NASA and released in mid-January, looks at the potential impact of a “super solar flare” followed by an extreme geomagnetic storm. According to NASA, the researchers looked at a huge geomagnetic storm that took place in 1921 (estimated to be 10 times stronger than the 1989 storm that left six million people in Quebec without power for nine hours). They then modeled its likely effects on the modern power grid.

Conclusion: the electrical power distribution system is likely to collapse across the eastern one-third of the U.S. as well as the Pacific Northwest, leaving more than 100 million people without power! Projected economic impact is some 20 times greater than that caused by Hurricane Katrina.

So enjoy those sunspots, but just hope the sun doesn’t get carried away with itself!

Source is [here](http://newsvc.cq-amateur-radio.com/) if you go to “View All.”

That’s scary stuff! Let’s hope it doesn’t cause too much harm.

So, I got this heating pad at the store a while back to use as a hedgehog heating pad. I found out that the 2-hour auto-off timer was hardcoded into the circuit, and they didn’t even bother to put a switch on the casing to disable it. Typical overprotection of the consumer – this wouldn’t exist if our country was a bit less litigious…

African hedgehogs need at least 72F to be happy, so a heating pad under the cage is recommended. I mean, how could you not help this face?:

So, to disable it, I decided to take it apart and find the culprit like this guy did. It’s too bad that for some reason they decided to make it even harder to change this “feature.” Here’s the outer casing:

Here is an overview of the circuit board:

It’s an Eagle LOPP4, and apparently it was made on Christmas of 2006 (2006-12-25)! It also bears a marking of 07.28, and I have no idea what that means.

So, the deal is that after a lot of trial and error, I finally found which single pin on the IC you have to cut. I’ve circled the IC here:

It’s PIN #2!

OK, it actually isn’t #2 on the schematic, but in the picture it makes sense. Just take a soldering iron and a sharp pointy object (I used a thumbtack), melt the solder, and pry the pin from the board. Be careful not to touch pin #1 – if you disconnect it, it will turn off every 5 minutes! Then, put the entire thing back together and celebrate!

I used the datasheet for the IC chip to figure out what pins to screw with. I can’t find the number of the chip right now without tearing the whole thing apart again. Basically, the chip is just a counter, and you cut one of the pins that makes it increment. So simple.

Now I have a happy hedgehog. He’ll never be cold again.

Update (1/2009)

Nick V has modified his Sunbeam Model 836. For those interested, here’s his description of the mod:

The chip is a CD4060 (14 stage ripple counter) on mine. They use it as count up timer to turn the ac to the heater coils off after two hours. I wired in a 10k resistor pullup to Vdd to pin 12 (master reset). This disables the counter function, and voila, no auto off!

I went ahead and found the datasheet for all you kids looking to try this. I extracted the one piece of information you probably need:

Nice job, Nick! Hats off to you!