Temperature sensor and real time clock for Arduino

 

This simple board has been developed to work together with an arduino board, but it can be used in conjunction with every other boards with an I2C bus and a power suplly into the range [2.7..5]V.


The schemathic for this board is shown in the following picture:

 

In the following table you'll find the complete BOM (Bill Of Materials):

 
Part Value Device Package Library Sheet
BAT   BATTERY20PTH BATTCOM_20MM_PTH SparkFun 1
C1 12p C-EU025-025X050 C025-025X050 rcl 1
C2 12p C-EU025-025X050 C025-025X050 rcl 1
C3 100nF C-EU025-025X050 C025-025X050 rcl 1
C4 10µF CPOL-EUE2.5-6 E2,5-6 rcl 1
C5 100nF C-EU025-025X050 C025-025X050 rcl 1
C6 100p C-EU025-024X044 C025-024X044 rcl 1
D1   DIODE-D-5 D-5 diode 1
D2 5.1v ZENER-DIODEZD-5 ZDIO-5 diode 1
D3   DIODE-D-2.5 D-2.5 diode 1
IC1 RTC DS1307SO8 SO08 SparkFun 1
IC2 TEMP MCP98011 SO-08 microchip_n 1
ICSP   PINHD-1X51X05_C 1X05_C pinhead 1
JP1   PINHD-1X71X07_C 1X07_C pinhead 1
JP2   PINHD-1X21X02_C 1X02_C pinhead 1
JP3   PINHD-1X21X02_C 1X02_C pinhead 1
L1   LED3MM LED3MM led 1
Q1 32.768k CRYSTALTC26H TC26H crystal 1
R1 1k R-EU_0204/2V 0204V rcl 1
R2 10k R-EU_0204/5 0204/5 rcl 1
R3 4.7k R-EU_0204/2V 0204V rcl 1
R4 4.7k R-EU_0204/5 0204/5 rcl 1
R5 3.3k R-EU_0204/2V 0204V rcl 1
R6 10k R-EU_0204/5 0204/5 rcl 1
R7 10 R-EU_0204/5 0204/5 rcl 1
R8 10k R-EU_0204/5 0204/5 rcl 1
R9 3.3k R-EU_0204/5 0204/5 rcl 1
R10 3.3k R-EU_0204/5 0204/5 rcl 1
R11 3.3k R-EU_0204/5 0204/5 rcl 1
T   PINHD-1X1 1X01 pinhead 1

 

The board takes the power supply linking the positive pin of the power supply (Max 5V) with the pin 1 (Vcc) of the pinheader Jp1, while the ground of the power supply shall be connected to the pin 1 (Gnd) of the pinheader Jp1. 

 

 

Tcn75 Sensor

Resistors R9,..,R11 are used to setup the tcn75 address on the I2C bus to 1. The solderpads set up the sensor address to 0.

The board is configured to have address value 7 on the I2C bus ( 0b10011 111 ).

If you want to change the address you shall unsolder one or more resistors and the link them to GND trough the solder pads A0 A0 A1 A2 as shown in the following table:


Tcn75 address on the I2C bus PIN A2 PIN A1 PIN A0
0 0 0 0
1 0 0 1
2 0 1 0
3 0 1 1
4 1 0 0
5 1 0 1
6 1 1 0
7 1 1 1

 

The alarm pin of the sensor is accessible on the pin2 of the pin header Jp2.


RTCC module

This module uses the same I2C bus of the temperature sensor. The alarm (also used to generate a rectangular wave form) is the pin 1 (SOW) on the pinheader Jp2

Interfacing an external microcontroller

An external microcontroller can be connected to the device using SDA and SCL signals on the pin header Jp1
The microcontroller can use the two alarm pins.

Important note: SDA and SCl pins shall be pullupped
The board provides 2 pull up resistors that can be enabled trough the two solder pads TD and TC. 
The 4.7 Kohm resistors allow up to 400 Khz speed of transmission on the I2C bus.


 

In the following picture you can see the top view of the board:

 


while in the following picture you can see the bottom view of the board:



We have some of these boards here
Gg1

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4 Responses

  1. December 23, 2011
  2. December 30, 2011

    […] Temperature sensor and real time clock for Arduino […]

  3. January 9, 2012

    […] Temperature sensor and real time clock for Arduino […]

  4. January 13, 2012

    […] Temperature sensor and real time clock for Arduino […]

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