Karl Patrick Gruenewald

My latest struggle with the PID project has been getting the LCD menu system to work right. I was able to get the basic readout, showing temp, target temp, machine uptime, and heat power pretty easily. But I wanted to have a way to change the target, show the PID internal values, enter a standby mode, and adjust backlight level. I put some plain buttons in my project box and got them to work with

(This post refers to software from the Bare Bones Coffee Controller project by Tim Hirzel on the Arduino playground.)So, I think I solved the problem with the temp sensing (see previous post). The thing that seems to have done it is to change the update interval to 2x per second from 5x:#define PID_UPDATE_INTERVAL 500 // millisecondsI re-read the PID without a PhD article, and it talks about

Here's a little problem I'm having with the PID. My temp spikes every time the Arduino turns on the digital pin connected to the SSR (to turn on the heater). Here's what the graph looks like:The measured temp goes up a couple of degrees when the Arduino is driving a digital pin attached to the SSR. Obviously, the actual temp isn't doing this. You can see that the duration of the error corresponds

When I first got my Silvia espresso machine about three years ago, I was really interested in all the mods people were doing. I did the pressure modification because it was relatively easy, cheap, and it seemed to me that it would improve my espresso. I really wanted to install a PID too, but I stopped short because using a commercial PID controller seemed overly expensive to me. So I learned to

I saw this post by Clive Thompson yesterday on Wired. It really sums up a lot of what I love about tweaking and tinkering with stuff. I get a lot of intellectual stimulation from learning about stuff and how to fix it. I also like the idea of reusing things that would otherwise go in the landfill and not buying new unless I have to.

This is the beginning of my blog to talk about my "personal" projects. The one I'm on right now is putting a PID controller on my Silvia espresso machine, using on the Arduino microcontroller. I'm basing it on work done by Tim Hirzel at the Arduino playground.The basic idea is to replace the stock brew thermostat with a solid state relay (SSR) to control the boiler heater. The SSR is controlled

I love these bikes. You see them all over the place here, hauling big loads.

Anya's school is having their xmas show tonight. Pretty cute, but a little long, especially for Collin who had a hard time sitting through all 2 hours.

Fire! We were sitting on the second floor balcony of a restaurant near our house, and heard lots of shouting from across the street. We looked over and a building under construction had black smoke billowing out. Quite the excitement for our Saturday afternoon.

Ciclovia is really cool. The city shuts down some of the major streets on Sundays and holidays for people to ride/run/whatever. The routes cover the whole city, and we're gradually trying to get out of the area we know.

The only problem with our apartment is that there are no bathtubs.

Here are Collin and Anya after having a big plate of chocolate waffles and ice cream for brunch.

Chanda and I went to Anya's class today and showed them how to make paper snow flakes (copos de nieve.) Since it doesn't ever snow in Bogota, not sure if it made any sense. But, it was still pretty fun.

Collin and Anya reading together very nicely.

The kids rode their bikes down the trail to the playground this morning. Maybe we'll hook up the trailer and take them on Ciclovia later.

Our friends invited us to a very nice club outside Bogota for a halloween party. Collin and Anya had a great time, especially on the jumping castle.

Since we are on now on our way to Bogota, I thought it would be a good time to restart the photo blog. Here is our luggage on its way to Miami. 8 suitcases, one carryon, two car seats, and all of our personal bags and such.

We are having Mother's Day brunch at the Botanic Gardens. We wish our moms and all moms a happy mother's day!

Anya is tired out from playing and eating sugar.

Collin, Jad, Chanda and I are taking a paddleboat ride in Forest Park while Anya naps at Grandma and Papaw's.

We're having coffee @ Park Avenue Coffee with Unka Jad. Next stop, Turtle Park.

Here's the doll house I'm building Anya for her birthday. It is my new lord and master.

Here's our little chef working on her own birthday cake. Happy birthday Anya!

Teller Elementary is getting part of the take from Steve's Snappin' Dogs today, so that'a where we're having lunch.

We're having an early spring here in Denver.

Anya is experimenting with self-decoration involving masking tape.

Found this tonight in our bathtub.

The weather is beautiful this afternoon. The kids are over the flu and back to their old selves.

Poor Anya and Chanda have the flu. Anya feels pretty lousy this morning.