different software times, impossible?

[richard]

try this

[lutherblisset]

400*300+300=240.000 us
1.000.000 us /240.000 us =4,1666666667
4,1666666667*400 pulses =1.666,66666668 hz for one second if the quartz is precise.......

[lutherblisset]

the pwm work good and the frequency counter confirm the exact frequency and its possible to stop it at a fixed point, now i need a second timer to count the y pulses other than 400) with a same time of x. The x train with 400 pulses do the work in: 400*300+300=240.000us. I need the same time for y, with pulses other than 400....

[lutherblisset]

what's the lowest possible increment in uS units of the two other timers with 20mhz quartz?

[richard]

what's the lowest possible increment in uS units of the two other timers with 20mhz quartz?

i think thats the wrong question

1. first thing is what time intervals are required to toggle the output at to achieve for the given number of pulses in the time frame
2. are they all possible within the available timer resolution ? how many pulses do you really need ? steps of 5 10, 50 ,1 ,2 ?
3. what method will be fast enough to toggle the output and count the pulses too .ie an isr or a fast loop to monitor timer overflows

PULSES TOGGLES PERIOD uS
100 199 1204.52
101 201 1192.54
150 299 801.67
200 399 600.75
250 499 480.36
300 599 400.17
350 699 342.92
400 799 300.00
450 899 266.63
500 999 239.94
550 1099 218.11
599 1197 200.25
600 1199 199.92

[lutherblisset]

hi richard, to match the x pulses (1666hz) for the y pulses i need to set a range from 500us (250high+250low) to 7500us (3750high+3750low) the increment can be 50us. For your 3rd question i need your help....

[richard]

if you go down that path then

toggle /time
pulses

250

479

300

399

350

342

400

299

450

266

500

239

550

217

600

199

650

184

700

171

750

159

800

149

850

141

900

133

950

126

1000

119

1050

114

1100

108

1150

104

1200

99

1250

95

1300

92

1350

88

1400

85

1450

82

1500

79

1550

77

1600

74

1650

72

1700

70

1750

68

1800

66

1850

64

1900

63

1950

61

2000

59

2050

58

2100

57

2150

55

2200

54

2250

53

2300

52

2350

51

2400

49

2450

48

2500

47

2550

47

2600

46

2650

45

2700

44

2750

43

2800

42

2850

42

2900

41

2950

40

3000

39

3050

39

3100

38

3150

38

3200

37

3250

36

3300

36

3350

35

3400

35

3450

34

3500

34

3550

33

3600

33

3650

32

3700

32

3750

31

then :-
1. your range is 31 to 479 pulses nothing like the 100-600 initially specified
2. not every period produces a different pulse count
3. pulses will not always finish synchronously within the 400 pulse stream
4. the pulse count varies in a non-linear manner