Your latest purchase

So I can use any existing 16Mhz bootloader (example: from Adafruit) with a 20/24 Mhz crystal, right? -- millis() timing may be off, but all the others should work fine as is.

The thing about the core is, the processor doesn't really know what speed it is running at. So for example if you use the 8 MHz internal oscillator everything will just be half the speed. So a 9600 baud rate for the serial port will really be 4800 baud. And delay (1000) will really delay 2000 mS.

Now for the bootloader, the problem will be it expects a certain baud rate. However if you change boards.txt to reflect the difference, it should work. So for example, for the Uno:

uno.name=Arduino Uno
uno.upload.protocol=arduino
uno.upload.maximum_size=32256
uno.upload.speed=115200
uno.bootloader.low_fuses=0xff
uno.bootloader.high_fuses=0xde
uno.bootloader.extended_fuses=0x05
uno.bootloader.path=optiboot
uno.bootloader.file=optiboot_atmega328.hex
uno.bootloader.unlock_bits=0x3F
uno.bootloader.lock_bits=0x0F
uno.build.mcu=atmega328p
uno.build.f_cpu=16000000L
uno.build.core=arduino
uno.build.variant=standard

Since the upload speed is normally 115200 you would need to increase that to 115200 * 24 / 16, which is 172800, assuming the USB chip can handle that speed.

However in my case I programmed with ICSP (not the bootloader) so that didn't apply. So, disclaimer: I didn't test with a bootloader.

Could you bootload at one speed and run at different?

Absolutely. All the bootloader does is put the program into program memory. You could then turn the power off, replace the crystal, and power it up again.

One of my offspring got one of these for Christmas. Have any of you seen them? Made in the UK and pretty nifty.

http://www.mikromart.com

Since when is Radio Shack reasonably priced? Went to the MALL store and got a Seeed Studio Proto Shield for $9.99!

Okay- Credit where credit is due.

Seeedstudio-- the protoshield kit is awesome. This is a great deal at ten bucks.
I expected the board headers and such, and not much else. However, they also toss in an extremely useful collection of common components: two red and two green LEDs, a bicolor LED, resistors for the LEDs, a 10k pot, two 40-strips of male pin headers, a 40-strip of female header, a 40-strip of long male headers, spare spacers, four tactile switches and two slide switches, and a USB socket. That's a heck of a lot for ten bucks!!!

I will be grabbing these again!

I finally bought an ISP for burning bootloaders, lol. Its apparently based on the USB ASP. Cost $7 on ebay.

I also bought a used server rack with UPS, 6 servers, a DAS, and a bunch of other junk. I'm probably going to use it to test an arduino based datacenter monitoring system.

Just got a partial shipment on what may be my last order from DX (DealeXtreme).
Got 50 40-pin header strips (steel, not brass pins), 10 keychain SD-micro/USB adapters and 3 IR signal receivers and a bag of jumpers. Still waiting on 10 2 mW laser modules (because at 45 cents ea, I'll make a use), 10 snap-in RJ-11 modular jacks, and 2 female-female 40 cm DuPont cables.

Well, I might order disc batteries from them but I can't say about that either.

24, yes 24 bit ADC module for less then $10. Let me count the bits, 1,2,3...yes 24 bits in all. So no need to have to amplify externally how level Wheatstone bridge type sensors, just read the millivolts, hell microvolts directly and still have more resolution then arduino's wimpy 10 bit ADC has.

We will have to see how the low noise performance of this module ends up with, as usually in the real world it's nearly impossible to actually be able to fully utilize 24 bits of resolution.

http://www.ebay.com/itm/121022291106?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Lefty

retrolefty:
Let me count the bits, 1,2,3...yes 24 bits in all.

Now count the possible combinations. I will get you started...

00000000 00000000 00000000
00000000 00000000 00000001
00000000 00000000 00000010
00000000 00000000 00000011
00000000 00000000 00000100

Go!

]:smiley:

I ordered three boards from OSHPark. Two are Silego breakout boards that I may or may not be able to solder, and one is an FTDI FT230x-based USB/Serial converter.

I'm also thinking about an FTDI VNC2-based "minishield" (USB Host), and an 8051 mini-system (But Why???), but those are aimed at Seeed/Itead (~50mm sq)

Just one of each, so I wont be making a LED cube of them :slight_smile:

Got one of CrossRoads' ATMega1284P Duemilanova-style boards. Soldered the parts on yesterday (except the FTDI header because I've ordered a USB board to go there).

The SMD soldering is challenging (that fuse kept escaping!), and I had trouble getting the voltage regulators soldered onto the heat sinks. Still, looks good, works fine. :slight_smile:

Lookin' good. I bought two of those blank PCB when Bob made them available. Built just one up so far and real happy with it. I didn't mount any regulators to mine yet, just jumpered Vcc to the DC jack and plug a regulated +5vdc to it. I'm using one of those cheap Asian CP2101 serial cables and it works fine.

Be sure to make the the small change to the bubuino variant file: pins_arduino.h or the pin mapping for the analog pins will be wrong:

// #define analogPinToChannel(p)	    ( (p) < NUM_ANALOG_INPUTS ? NUM_ANALOG_INPUTS - (p) : -1 )
#define analogPinToChannel(p)       ( (p) < NUM_ANALOG_INPUTS ? (NUM_ANALOG_INPUTS-1) - (p) : -1 )

Might be a few other changes to the maniac supplied files, I don't recall at the moment.

EDIT: Some people were having reliability problems with the serial port working on the 1284P DIP (but not on bobuino boards!) and lots of different fixes were tried to different effectiveness, but what seemed to nail it for experiencing such problems is changing the low fuse byte to use full swing oscillator: bobuino.bootloader.low_fuses=0xf7
So probably a good change to make on general purposes.

EDIT2: By the way getting a 644P working on this board is a piece of cake just add new board entry:

##############################################################

bobuino644.name=Bobuino 644P optiboot
bobuino644.upload.protocol=arduino
bobuino644.upload.maximum_size=63488
bobuino644.upload.speed=115200
bobuino644.bootloader.low_fuses=0xff
bobuino644.bootloader.high_fuses=0xdc
bobuino644.bootloader.extended_fuses=0xfd
bobuino644.bootloader.path=optiboot
bobuino644.bootloader.file=optiboot_atmega644p-4-5.hex
bobuino644.bootloader.unlock_bits=0x3F
bobuino644.bootloader.lock_bits=0x0F
bobuino644.build.mcu=atmega644p
bobuino644.build.f_cpu=16000000L
#bobuino644.build.core=arduino:arduino
bobuino644.build.core=standard
bobuino644.build.variant=bobuino

##############################################################

And here is a optibootloader setup for the 644P: optiboot_atmega644p-4-5.hex

:020000000504F5
:10FC0000112484B714BE81FFF2D085E08093810077
:10FC100082E08093C00088E18093C10086E08093F9
:10FC2000C20080E18093C4008EE0CBD0209A86E0B1
:10FC300020E33CEF91E0309385002093840096BB55
:10FC4000B09BFECF189AA8958150A9F7CC24DD244B
:10FC500088248394B5E0AB2EA1E19A2EF3E0BF2E69
:10FC6000A4D0813471F4A1D0082FB1D0023811F49E
:10FC700085E005C0013811F484E001C083E08DD037
:10FC800089C0823411F484E103C0853419F485E01D
:10FC9000A6D080C0853579F488D0E82EFF2485D0A1
:10FCA000082F10E0102F00270E291F29000F111F09
:10FCB0008ED068016FC0863521F484E090D080E05A
:10FCC000DECF843609F040C070D06FD0082F6DD0E1
:10FCD00080E0C81680EED80618F4F601B7BEE895A5
:10FCE000C0E0D1E062D089930C17E1F7F0E0CF16C5
:10FCF000F0EEDF0618F0F601B7BEE89568D007B65B
:10FD000000FCFDCFA601A0E0B1E02C9130E01196FF
:10FD10008C91119790E0982F8827822B932B129625
:10FD2000FA010C0187BEE89511244E5F5F4FF2E0A7
:10FD3000A030BF0751F7F601A7BEE89507B600FC53
:10FD4000FDCF97BEE89526C08437B1F42ED02DD0D4
:10FD5000F82E2BD03CD0F601EF2C8F010F5F1F4FF8
:10FD600084911BD0EA94F801C1F70894C11CD11CFE
:10FD7000FA94CF0CD11C0EC0853739F428D08EE10F
:10FD80000CD086E90AD08AE07ACF813511F488E078
:10FD900018D01DD080E101D063CF982F8091C00092
:10FDA00085FFFCCF9093C60008958091C00087FF27
:10FDB000FCCF8091C00084FD01C0A8958091C60051
:10FDC0000895E0E6F0E098E1908380830895EDDF08
:10FDD000803219F088E0F5DFFFCF84E1DECF1F939A
:10FDE000182FE3DF1150E9F7F2DF1F91089580E04B
:08FDF000E8DFEE27FF2709946C
:040000030000FC00FD
:00000001FF

Lefty

I bought a few of these for $8:

http://www.ebay.com.au/itm/261132296135

MAX7219 chip plus a 8x8 LED plus PCB (not assembled).

The MAX7219 alone is around $19 for one from Farnell. OK, it's $8 if you buy 100.

But this kit includes the 64-LED display as well! And the circuit board. And two capacitors and a resistor. And the edge connectors. And the chip socket. And socket strips for the LED display.

They are designed to be daisy-chained (haven't quite got that sorted yet).

retrolefty:
Be sure to make the the small change to the bubuino variant file: pins_arduino.h or the pin mapping for the analog pins will be wrong:

// #define analogPinToChannel(p)	    ( (p) < NUM_ANALOG_INPUTS ? NUM_ANALOG_INPUTS - (p) : -1 )

#define analogPinToChannel(p)       ( (p) < NUM_ANALOG_INPUTS ? (NUM_ANALOG_INPUTS-1) - (p) : -1 )




Might be a few other changes to the maniac supplied files, I don't recall at the moment.

EDIT: Some people were having reliability problems with the serial port working on the 1284P DIP (but not on bobuino boards!) and lots of different fixes were tried to different effectiveness, but what seemed to nail it for experiencing such problems is changing the low fuse byte to use full swing oscillator: bobuino.bootloader.low_fuses=0xf7
So probably a good change to make on general purposes.

Thanks for the suggestions.

Over the past weekend I went to a local hamfest and picked up a Heathkit ET-3400; it's basically a small 8-bit (Motorola 6800) computer with 512 bytes of memory, some LEDs, a hex keyboard (and 7-segment hex display), ROM monitor software (so you can enter assembler opcodes, and debug, etc) - plus a breadboarding area (which a previous owner had set up a 6821 PIA interface). Also got the manuals for it...

I spent $50.00 for it; Yeah - I could've gotten a Raspberry Pi or a Mega for cheaper - but I can guarantee you neither would be as cool as this monstrosity...hehehe.

:smiley:

picked up a Heathkit ET-3400;

Back in the day I had a Micro Professor which was a similar thing for the Z80 (Z80-based CP/M machines were in vogue). I got a few extras for it, like a Tiny-Basic chip.

Bloody thing got stolen from my office while I was on leave...

http://www.ebay.com/itm/250828820487

10 pcs MAX7219CNG - $4.80, free shipping.

Just sent an order to them, also got:

2PCS Arduino NRF24L01+ Wireless Transceiver Module $2.60
10PCS OPTOCOUPLERS FAIRCHILD/MOTOROLA DIP-6 MOC3041 $3.79
1 Channel Isolated 5V Relay Module $2.18
1PCS IC ATMEL DIP-28 ATMEGA328-PU $3.99 (this is a little high)

and a couple other doodads.. however, when I saw that price you said for 7219's, I figured you may want to snap a few of these up!

This is just getting insane. I wonder if they work?

Anyway just ordered 20 for under $10 including free shipping.