Installing Code for PiFace Real Time Clock

Question

Dear Element 14 Community.

All my Raspberry Pi devices (RPi 2, RPi Zero, and RPi 3 (planned) are running with the current Raspbian Jessie version. I have successfully installed PiFace Real Time Clock using the PiFace website instructions and GitHub.com software download on a number of RPi 2's and one of my three RPi Zero's.

I have recently continued the installations on another two RPi's and cannot continue because after these two lines:

1. chmod +x install-piface-real-time-clock.sh

2. sudo ./install-piface-real-time-clock.sh

The following new comments are returned: 1

1.. create new pifacertc init script to load time from PiFace RTC

2. Adding /etc/init.d/pifacertc .

3. install the pifacertc init script

4. enable I2c by using raspi-config

As I am a Linux beginner, can someone lead me through (expand) the coding of these lines so I may install PiFace RTC currently and in the future. The changelog on GitHub refers to a revision change but I am not knowledgable enough to understand why the install went through previously by not currently.

Thank you very much,

Frank.

Former Member · Answer

Im going to try and re-write this script, rather than trying to determine the revision of the raspberry pi to workout which i2c port to address, it can be simplified to ls /dev | grep "i2c" This should get the device directly rather than guessing based on the model.

Workshopshed · Answer

Hi Frank,

looking at that file it appears to be checking if the I2C system is enabled. That's the communications used to talk to the real time clock.

raspi-config is a command line tool for changing the Pi's configuration. You can run that by typing

sudo raspi-config

You can the find the right screen to turn on I2C. It appears to be in the advanced options.

Former Member · Answer

Are those all of the comments that are returned? Having a glance at the install script it seems there should be a piece saying to reboot and another demonstrating how to set the clock etc... If these are missing it would indicate that the install script has not completed correctly. Has the install script created the /etc/init.d/pifacertc file? check by typing cat /etc/init.d/pifacertc into a terminal window, there should be around 37 lines of text print out into the terminal as a result. If the installer hasnt completed succesfully it should be easy enough to replicate the procedure manually, everything is provided in that script to do that. p.s.the comments 1,2 and 3 that appear ate just the install script telling you where it is up to. Comment 4 is an instruction to you to run raspi-config, as I said above, there should also be more text below this

Former Member · Answer

Hah! Thats just linux being pig headed, run the chmod command using sudo like below. The idea being that if a user doesn't have permission to execute a file then the system isnt going to confirm that files existence either so rather than saying permission denied, it just says file not found etc... It discourages repeat attempts at illegally executing files I think! sudo chmod +x ./pifacertctest.sh Ive just completed the steps of downloading using wget, then sudo chmod etc.. to test it out and can confirm it does work using sudo! edit (the below is nothing to do with the question, its just some further reading!!) -------------------------------------------------------------------------------------------------------------- The chmod case can be quite confusing, if you are interested here is an explanation why we need to use sudo chmod in this case. 1) If we use chmod +x ./pifacertctest.sh the file becomes executable for the logged in user, on the raspberry pi that user is called "pi" 2) We need to execute the file using sudo ./pifacertctest.sh using sudo means we are no longer acting as the user "pi" but we are acting as the user "root" (or with root user privileges) 3) because the pifacertctest.sh has been made executable for the user "pi" and NOT the user "root" when we try and execute it with root priviliges (sudo), the root user doesn't have the executable permission 4) if we use sudo chmod +x ./pifacertctest.sh the file becomes executable for the root user, this is because we used sudo 5) Now the root user has permission to execute the file, its now possible to do with sudo ./pifacertctest.sh 6) if the script didnt need executing with root privileges (sudo) then we wouldnt have to sudo chmod.