1. Flowchart Symbols
What do these mean:

2. 2007: Q6
A student has decided to use a µC for a steady hand game. His system diagram is below µC
LED 1 (life 1)
Output 0
LED 2 (life 2)
Output 1
Wand & Contacts
Input1
LED 3 (life 3)
Output 2
Transducer driver
Buzzer
Output 3

3. Requirements
A:Each time the wand & track touch, the µC switches on & an LED in sequence 1, 2 & 3. Once an LED is lit it will stays lit until reset (9 marks)
B: once the wand & track touch, the µC will ignore any further contact between the wand & track for 2 seconds (4 marks)
C: On the loss of the third life, the buzzer will switch on for 0.25s, then switch off for 0.25s. This is repeated 3 times (6 marks)
The µC will then reset back to “no lives lost” (3 marks)
Total: 22 marks

4. START 2007 ELECTRONIC PRODUCTS Requirement ‘A’ Sample answer 9 marks
Has Wand made contact NO
YES
Output 0 = 1
Has Wand made contact NO
YES
Output 1 = 1
Has Wand made contact NO
YES
Output 1 = 1
END

5. START 2007 ELECTRONIC PRODUCTS Requirement ‘B’ Sample answer
Additonal 4 marks
WAND ? NO
YES
WAIT 2S
OUTPUT0=1
WAND ? NO
YES
WAIT 2S
OUTPUT0=1
WAND ? NO
YES
WAIT 2S
OUTPUT0=1
END

6. 2007 ELECTRONIC PRODUCTS START Requirement ‘C’ Sample answer
Additional 6 marks
START
WAND ? NO
SUB0
YES
WAIT 2S
COUNT=1
OUTPUT0=1
OUTPUT3=1
WAND ? NO
WAIT 0.25
YES
WAIT 2S
OUTPUT3=0
OUTPUT0=1
WAIT 0.25
WAND ? NO
COUNT=3
YES
RETURN
YES NO
WAIT 2S
COUNT= COUNT + 1
OUTPUT0=1
SUB 0
END

7. 2007 ELECTRONIC PRODUCTS START Requirement ‘D’ Sample answer
Additional 3 marks
START
WAND ? NO
SUB0
YES
WAIT 2S
COUNT=1
OUTPUT0=1
OUTPUT3=1
WAND ? NO
WAIT 0.25
YES
WAIT 2S
OUTPUT3=0
OUTPUT0=1
WAIT 0.25
WAND ? NO
COUNT=3
YES
RETURN
YES NO
WAIT 2S
COUNT= COUNT + 1
OUTPUT0=1
SUB 0
ALL OUTPUTS=0