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2.8" TFT + Touch Shield + DS1307 RTC

Posted: Sun Feb 09, 2014 9:20 am

by texy

Setup instructions for this new design based on my 2.8" TFT, but with a DS1307 RTC option.

First, setup the screen and touch panel by following the instructions here :
http://www.raspberrypi.org/phpBB3/viewt ... 45&t=64993

Then to setup the RTC :
If possible ensure a valid internet connection is made on the Pi to get an accurate time and date. Also fit a CR2032 lithium battery in order to maintain correct time and date on power loss to the Pi.
The DS1307 is an I2C device, so that bus needs to be enabled. Edit the /etc/modules file

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sudo nano /etc/modules

Add

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i2c-bcm2708
i2c-dev

before the

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ads7846_device swap_xy=1 gpio_pendown=17 x_plate_ohms=100 pressure_max=255

line.
Then remove the i2c-bcm2708 line from the blacklist file

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sudo nano /etc/modprobe.d/raspi-blacklist.conf

put a # in front of the

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blacklist i2c-bcm2708

line and save it.
Install the python-smbus package

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sudo apt-get install python-smbus -y

This will also install the i2ctools package as a dependency.
At this point reboot the pi

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sudo reboot

After the restart check the pi can see the ds1307

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sudo i2cdetect -y 1

for Rev 2 Pi's
or

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sudo i2cdetect -y 0

for Rev 1 Pi's
and the following should be reported

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[email protected] ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Note the '68' detected is the ds1307.
Now that the i2c bus is set up, we need to load the driver for the ds1307

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sudo modprobe rtc-ds1307

We need to be root to do the next bit

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sudo bash

then

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echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
exit

If you then

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sudo i2cdetect -y 1

again you should see

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[email protected] ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Notice the 'UU' at address 68 - this means that the ds1307 is under control of the driver. To test this use

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sudo hwclock -r

If there is no valid internet connection to the Pi, the time may not be correct and it will need to be set manually.
Once the system time is correct it can be written to the ds1307 with

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sudo hwclock -w

You should then get the correct time and date with

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sudo hwclock -r

In order to load the ds1307 module upon a reboot of the Pi you'll need to add it to /etc/modules

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sudo nano /etc/modules

and enter

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rtc-ds1307

after the i2c-dev line you entered earlier.
Then the ds1307 device needs creating by adding it to the /etc/rc.local file

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sudo nano /etc/rc.local

and adding

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echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
sudo hwclock -s

for a Rev 2 Pi, or

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echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device (v2 raspberry pi)
sudo hwclock -s

for a Rev 1 Pi before the

exit 0

line.
Power off the Pi, leave it off for a while, then repower it and check the time and date are still correct.
Texy

Re: 2.8" TFT + Touch Shield + DS1307 RTC

Posted: Thu Jun 05, 2014 10:58 am

by icarus

Hi Texy,

For some reason I cannot send you a personal message. So I reply here.
Do you have any of these board for sale? I'm interested in a "2.8" TFT + Touch Shield + DS1307 RTC". I also read you have a case compatible with this shield.

Re: 2.8" TFT + Touch Shield + DS1307 RTC

Posted: Thu Jun 05, 2014 4:55 pm

by texy

Hi
You need to have your first post approved before you can pm.
You can now pm

Yes I have stock.
Texy