breadboard_collections

K-Timer

[October 2015] Originally created.

UNDER CONSTRUCTION and source code not yet available

Single Digit Kitchen Timer. Simple Construction

Description

This is single digit timer project based on the msp430f2011 (or equivalent). It can be assembled with minimal parts. With one digit 7 segment display show minute units, this timer counts down at half-minute intervals. Half minutes are show w/ the decimal point.
IMG

Each key-press adds half minute to the count down. The timer has a range of half minutes up to 9.5 minutes.

The lone 7 segment display shows the remiaing time in minutes, with the decimal point indicating 1/2 minutes. Display blinks a few times when reaching each half-minute intervals.

Buzzer will sound off and display flashes when time is up. Pressing the button will stop the alarm and place the timer into deep sleep mode.

Upon next activation the timer starts showing the setting (time to count down) of the last activation.

The circuit employs 7 output pins to drive the led segments directly. Current limiting resistors are eliminated to save breadboard estate and the led segments are not lit at all times so as not to burn out the led.

Features

Parts list


IMG

Application Notes

Breadboard Layout


   +=====================================================+
   |  .  o-----------------------o  .  .  .  .  .  .  .  |
   |  . (-) .  .  .  .  .  o+BZR=o  .  .  .  .  .  .  .  |
   |                \   .  |  .  .  .  G  F  +  A  B  .  |
   |                 :  .  |  .  .  o-----o  .  .  .  .  |
   | CR 2032         :  .  |  .  +--+--+--+--+--+--+     |
   | Battery Holder  :     |    |- b6 b7 CK IO a7 a6| .  |
   |                 :     |    |+ a0 a1 a2 a3 a4 a5|    |
   |                 :  .  |  .  +--+--+--+--+--+--+  .  |
   |                 :  .  |  .  .  .  E  D  +  C  d  .  |
   |                /.  .  +--------o  .  .  .  .  .  .  |
   |  . (+) .  .  .  .  .  .  .  .  o-[Btn]--o  .  .  .  |
   |  .  o-----------------------o-----------o  .  .  .  |
   +=====================================================+


IMG

Schematic


         /|\                MSP430F2011
          |              -----------------          Vcc
          +-------------|RESET            |         /|\
                N.C. <--|TEST             |          |
                        |                 |   _|_    |
                        |             P1.0|--o   o---+----( Buzzer )--+
                        |             P1.1|--> SEG E                  |
                        |             P1.2|--> SEG D                 _|_
                        |             P1.3|--> Vcc                   ///
                        |             P1.4|--> SEG C
                        |             P1.5|--> SEG D
               SEG F <--|P2.6(XIN)    P1.6|--> SEG B
               SEG G <--|P2.7(XOUT)   P1.7|--> SEG A
                        |                 |

Assembling

The layout of components are restricted by the mini breadboard available junctions. The MCU’s CK and IO (reset) pins are not isolated as the placement of the LED module does not allow that. There will be some ghosting on LED segment F caused by the fact that CK pin is not isolated. To avoid this we can isolate this pin by putting a “sleeve” on this pin. The sleeve is acutally the coating of a breadboard wire (I am using Cat3 cables).

Source code

Source code usually resides in my github repositories.

For this particular project, the single C source file ktimer.c is bundled in my breadboard collections repository. You just need ktimer.c