Raspberry Pi 2 built-in LEDOctober 24, 20152 min read For an assignment in my robotics class, I need to have an autonomous system react to the environment around it. Reacting can be as simple as flashing a LED if a sensor detects a change. I have two objectives for the Raspberry Pi 2 (RasPi2) and those are to take a picture using the 5mp webcam and flash a LED. I could use the standard GPIO pins and setup a separate LED but noticed we have two perfectly good LEDs built into the board. Reading on these built-in LED did not elicit any clear way of interacting with them from the regular Linux documentation. I informally called them the Red Power and Green DiskIO LEDs. It was by reading the headers to the source for Windows 10 for Raspberry Pi 2 that I found the GPIO pinouts for these two LEDs. They are: 35 Red Power LED 47 Yellow DiskIO LED read more Python TimeDate functionsMarch 19, 20151 min read I needed a quick understanding of the Python 3.3.0 datetime functionality to do a difference in times across days. Python make it amazingly easy. import datetime from datetime import timedelta # get current timedate now = datetime.datetime.now() print "now: " + str(now) # get one day of time oneday = timedelta(days=1) # make one day in the future and past tomorrow = now + oneday yesterday = now - oneday print "tomorrow: " + str(tomorrow) print "yesterday: " + str(yesterday) # compare times if now < tomorrow: print "now < tomorrow" elif now > tomorrow: print "now > tomorrow" else: print "now must be equal tomorrow" if now > yesterday: print "now > yesterday" elif now < yesterday: print "now < yesterday" else: print "now = yesterday" The expected results are: CMD> python time.py now: 2015-03-19 14:30:31.083000 tomorrow: 2015-03-20 14:30:31.083000 yesterday: 2015-03-18 14:30:31.083000 now < tomorrow now > yesterday I hope this helps someone. read more Rackspace Cloud Load Balancer with Windows 2012 IISMarch 11, 2015Less than 1 min read I’m working on a problem with Windows 2012 RTM server running an IIS web service. To load balance it, we decided to use Rackspace Cloud Load Balancers. Periodically we receive some errors that appear in the system event logs. "A fatal alert was generated and sent to the remote endpoint. This may result in termination of the connection. The TLS protocol defined fatal error code is 40. The Windows SChannel error state is 1205." read more Wildcard SSL CertificatesFebruary 27, 20151 min read I’m beginning to setup enough infrastructure that a wildcard certificate would be nice but I’m uninterested in paying several hundred dollars a year for that certificate. The free certs that used to be around just are not there anymore so far as I can see. My goal is to setup SSL certificates for both my email server and all the virtual host web sites I’m hosting under my mcgarrah.org domain for less than a hundred dollars a year. read more Posts 2015-10-24 Raspberry Pi 2 built-in LED 2015-03-19 Python TimeDate functions 2015-03-11 Rackspace Cloud Load Balancer with Windows 2012 IIS 2015-02-27 Wildcard SSL Certificates
Raspberry Pi 2 built-in LEDOctober 24, 20152 min read For an assignment in my robotics class, I need to have an autonomous system react to the environment around it. Reacting can be as simple as flashing a LED if a sensor detects a change. I have two objectives for the Raspberry Pi 2 (RasPi2) and those are to take a picture using the 5mp webcam and flash a LED. I could use the standard GPIO pins and setup a separate LED but noticed we have two perfectly good LEDs built into the board. Reading on these built-in LED did not elicit any clear way of interacting with them from the regular Linux documentation. I informally called them the Red Power and Green DiskIO LEDs. It was by reading the headers to the source for Windows 10 for Raspberry Pi 2 that I found the GPIO pinouts for these two LEDs. They are: 35 Red Power LED 47 Yellow DiskIO LED read more
Python TimeDate functionsMarch 19, 20151 min read I needed a quick understanding of the Python 3.3.0 datetime functionality to do a difference in times across days. Python make it amazingly easy. import datetime from datetime import timedelta # get current timedate now = datetime.datetime.now() print "now: " + str(now) # get one day of time oneday = timedelta(days=1) # make one day in the future and past tomorrow = now + oneday yesterday = now - oneday print "tomorrow: " + str(tomorrow) print "yesterday: " + str(yesterday) # compare times if now < tomorrow: print "now < tomorrow" elif now > tomorrow: print "now > tomorrow" else: print "now must be equal tomorrow" if now > yesterday: print "now > yesterday" elif now < yesterday: print "now < yesterday" else: print "now = yesterday" The expected results are: CMD> python time.py now: 2015-03-19 14:30:31.083000 tomorrow: 2015-03-20 14:30:31.083000 yesterday: 2015-03-18 14:30:31.083000 now < tomorrow now > yesterday I hope this helps someone. read more
Rackspace Cloud Load Balancer with Windows 2012 IISMarch 11, 2015Less than 1 min read I’m working on a problem with Windows 2012 RTM server running an IIS web service. To load balance it, we decided to use Rackspace Cloud Load Balancers. Periodically we receive some errors that appear in the system event logs. "A fatal alert was generated and sent to the remote endpoint. This may result in termination of the connection. The TLS protocol defined fatal error code is 40. The Windows SChannel error state is 1205." read more
Wildcard SSL CertificatesFebruary 27, 20151 min read I’m beginning to setup enough infrastructure that a wildcard certificate would be nice but I’m uninterested in paying several hundred dollars a year for that certificate. The free certs that used to be around just are not there anymore so far as I can see. My goal is to setup SSL certificates for both my email server and all the virtual host web sites I’m hosting under my mcgarrah.org domain for less than a hundred dollars a year. read more