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Topics - brett

Project logs / Brett's Solar Inverter custom PCB
Thought I'd list my current activity here for interest.  This is a low priority project but one that I am sure others can comment on and provide guidance.

I have a solar inverter that has a RS232 serial port that I can extract information about the output from. I have a low powered PC connected to that and sending data up to the web service, so I can track the panel's production in near real time. Eventually I'd like to be able to see much closer to real-time data than the 10 minute cycle that it currently has, and remove the need for a PC and replace that with a microcontroller - I am using a Fez Panda for this task.

My one-off custom PCB that I intend to make at home needs to have a number of things:
* a way to connect the Fez uC to it (this will be arduino-like headers)
* a MAX232 chip for the RS232 comms
* a PCB mount DB9 connector
* a socket for a Wiznet WIZ812MJ for ethernet connectivity
* a 24LC256 I2C eeprom to store config data like MAC address to
* a SD card holder to log data to, for archival purposes (and potentially using in an RRD database after-the-fact)
... and all fit within the inverter's case, as well as not exceeding the free Eagle board constraints.

I have started with a set of Eagle design files for the Panda and stripped out the unnecessary components, leaving me with just the footprint of the connectors. I have created a footprint for the SD card (one major piece of work because the one I bought at Jaycar isn't anything like a "standard"). I have laid out everything where I think it needs to be, and had a go at routing it all; but there are many issues I need to correct because some of the defaults in Eagle won't be easy to do in a home-built PCB, for example the default pad size on a via is way too small for hand drilling, especially since I don't have a drill press!  [ As an aside, I'd be interested to hear from others who drill PCBs at home what you use; I have a dremel-like tool but no drill press of any kind]
General discussion / the blog comments leaks email addresses
Hi Ian and team

i've noticed of late that the blog post "Comments" section is retaining the last person to make a comment's details, instead of retaining my details as it used to do (monthsssssssssss ago, 6-12 months ago since I left a comment). 

I normally visit the posts directly from an RSS feed post or perhaps from tweets. When i do, I can see email addresses from other people who have left comments and it could be a way to loose confidential info; in fact it looks like server sessions are screwing up. 

Ian, can you email me off list so I can tell you more?
Bus Pirate Support / BP with AVRDude - pointers/guidance request
OK, so I've borked my Wiz200web module (a ATMEGA128 and ethernet chip).  I uploaded a precompiled firmware using the bootloader that either went wrong or overwrote the bootloader code inadvertently (all my fault, I didn't really think too much about what I was doing).

So now I want to write a new firmware with bootloader to the device, and since I don't have anything like a USB programmer (my current programmer is a parallel jobbie for my specific ATMEGA32 dev board I have) I thought "This sounds like a job for.... BusPirate!"

I failed twice ! :)

I worked through Michal's process, and the end result is that I think my uC isn't responding correctly.  I'm pretty sure I targetted the right pins on the AVR module, I can see there's power to the atmega board, and I can see BP responding to AVRDUDE (when it lists the firmware info) but then I get an invalid signature returned, as it's showing all zeros for the ID.  To me that means SPI isn't working/connected correctly.  No idea whether this is connection related, ie me going crosseyed and wiring up breadboards too late at night, or whether it's related to the fact that the pinouts on this board interconnected in a special way (pullups?) , or even if there is an issue with the MEGA that I've introduced because of my failed upgrades.

So, does anyone have any thoughts?  Is there a way the upload process could have gone so wrong that this kind of thing would have happened?  Can anyone think of tests I can do to suss this out a bit more?  (SPI manual commands??)

thanks in advance !
#twatch network LCD backpack / power over ethernet injectors
Found a cheap-ish plug solution to allow you to run power to your #twatch or similar device instead of being tethered to running near a power outlet. ... 3efc5c8c64

(hoping link to ebay works - if not search for item 270521896036)

Even some hand-crafted ones for a simple DC power bus would allow you to run a single plug pack (with enough amperage of course) at the "wiring closet" and run multiple devices on the end of the ethernet cables.
General discussion / DNS or web server for WhereIsIan/forum - issues?
just checking whether it's me or whether everyone else sees this at times?

Occasionally, I try to visit the forum and either DNS isn't working or the web server is not responding.  Try refresh in a few minutes and most times it's back.

Was wondering if this is "known" (ie constraint of ISPs or hosting plans etc etc) or whether it's potentially just my connection being flaky?  I don't think i've ever seen this kind of behaviour over at the blog on
DIY Life projects / the prototype board....
when will it appear on the "sunday freebie" list? ;-)

Is it just me or did this section just pop up since it's Feb, even though the project was 2 years old?  Of course it coulda been my inattention to that section of the main forum page, or my heightened awareness of Valentines Day looming closer :)

mm, now $1 AVRs that fit the bill.... time to research it ! ;-)
General discussion / microcontroller - switch debounce time
I'm pretty new to all things uC, well ok pretty much a novice with a little bit of experience spread over a long time (nobody call me a slow learner, ok :) )

Anyway, if you've ever debounced a switch, how long do you wait?  10ms? 100ms?

i have a timer triggering 1ms interrupts, and am wondering how frequently I should check for switch contact (thinking ~25ms initially?) and how long to wait before "confirming" switch contact. Thoughts?