 |
 |
|
 |
 |
ZBasic System Library
177
ZX Microcontroller Family
OpenPWM
Type
Subroutine
Invocation
OpenPWM(channel, frequency, mode)
OpenPWM(channel, frequency, mode, stat)
Parameter
Method
Type
Description
channel
ByVal
Byte
The channel to use for PWM generation.
frequency
ByVal
Single
The desired PWM frequency.
mode
ByVal
Byte
The desired PWM mode (see discussion below).
stat
ByRef
Boolean
The variable to receive the status code.
Discussion
This subroutine prepares a PWM channel for generating a pulse width modulated (PWM) signal. PWM
generation is performed using one of the CPU’s 16-bit timers, the number of which varies depending on
the ZX model. The table below indicates the available channels and the corresponding timer used. See
the description of PWM() for additional details on the PWM channels.
Supported 16-bit PWM Channels
ZX Models
Timer
Channels
ZX-24, ZX-24a, ZX-24p, ZX-24n,
ZX-40, ZX-40a, ZX-40p, ZX-40n,
ZX-44, ZX-44a, ZX-44p, ZX-44n,
ZX-328n, ZX-328l, ZX-32n, ZX-32l,
ZX-24e, ZX-24ae, ZX-24ne, ZX-24pe,
ZX-24nu, ZX-24pu, ZX-328nu
Timer1
1, 2
ZX-24r, ZX-24s, ZX-40r, ZX-40s, ZX-44r, ZX-44s
ZX-24ru, ZX-24su
Timer1
Timer3
1, 2
3, 4
ZX-1281, ZX-1281n,
ZX-128e, ZX-128ne, ZX-1281e, ZX-1281ne
Timer1
Timer3
1, 2, 3
4, 5, 6
ZX-1280, ZX-1280n
Timer1
Timer3
Timer4
Timer5
1, 2, 3
4, 5, 6
7, 8, 9
10, 11, 12
ZX-24x, ZX-32a4, ZX-24xu
TimerD0
TimerD1
TimerC0
TimerE0
1, 2
3, 4
5, 6, 7, 8
9, 10, 11, 12
ZX-128a1
TimerD0
TimerD1
TimerC0
TimerE0
TimerE1
TimerF0
TimerF1
1, 2
3, 4
5, 6, 7, 8
9, 10, 11, 12
13, 14
15, 16, 17, 18
19, 20
The frequency parameter specifies the PWM base frequency in Hertz. Since the same frequency and
generation mode will be used for all PWM channels based on the same timer, it is only necessary to call
OpenPWM() once to prepare the timer for all of the PWM channels that are based on a given timer.
The mode parameter specifies the PWM generation mode. Two modes are supported: Fast PWM mode
and Phase/Frequency Correct mode. The constants zxFastPWM and zxCorrectPWM, having the values
0 and 1 respectively, may be used to specify the mode. The Fast PWM mode has a maximum frequency
of one-half of the CPU clock frequency and is intended for fixed-frequency applications. The
Phase/Frequency Correct PWM mode has a maximum frequency of one-quarter of the CPU clock
|
 |
|