Pulse Mode


Overview

This mode is used to precisely generate rectangular wave, which can be a single pulse or a chain of pulses. The pulses are identical to each other.

Waveform of HT pin will:

Available Commands

Command Sub Command Description
set mode output pulse set mode: pulse
div ms set unit: millisecond
us set unit: microsecond
output od open-drain
pp push-pull
low output: LOW
high output: HIGH
invert 0 not invert output
1 invert output
count [T1] [T2] set output timing parameters
repc [N] set repeat count
trigger from ht0 set trigger target: ht0
php set trigger target: none
reset - reset
get state get current state
div get division rate
repc get remaining repeat count
start - start
stop - stop

Set Repeat Count

In output pulse mode, this command is used to set the number of pulses.

Command Syntax Vaild range of N
set repc pid_ioctl($pid, "set repc N"); 0 to 64

If the command is not used, the default value is zero. Setting this value to zero means the maximum repeat count (64).
(see example of waveform in "Set Count Values" section)

Set Count Values

A rectangular pulse is composed of high-level signal and low-level signal. In output pulse mode, this command is used to specify the durations signal stays in low-level and high-level during a pulse. The unit of time is specified in "set div" command.

Command Syntax
set count pid_ioctl($pid, "set count T1 T2");

Valid values for T1 and T2 in pulse mode are as follows:

Division Available Count Values
T1 1 ~ 32763
T2 1 ~ 32763
T1 + T2 2 ~ 32764

This command must be used before timer starts. If not, an error is generated.
The figure below shows waveform in the case of:

ht_set_pulse_01

Set Output [low/high]

This command immediately forces HT pin to LOW or HIGH.

Command Syntax Description
set output low pid_ioctl($pid, "set output low"); Set HT pin to LOW
set output high pid_ioctl($pid, "set output high"); Set HT pin to HIGH

Note that if invert mode is enabled, this command will force HT pin to the state that is invert of normal operation.

Set Output [od/pp]

This command set output type of HT pin

Command Syntax Description
set output pp pid_ioctl($pid, "set output pp"); Set output type to push-pull
set output od pid_ioctl($pid, "set output od"); Set output type to open-drain

If the command is not used, the output type of HT pin is push-pull by default.

Set Output Invert [0/1]

This command is used to enable/disable invert mode.

Command Syntax Description
set output invert 0 pid_ioctl($pid, "set output invert 0"); disbale invert mode
set output invert 1 pid_ioctl($pid, "set output invert 1"); enable invert mode

When invert mode is enabled:

When the invert mode is changed (from enabled to disabled or vice versa), HT pin is toggled immediately. In other words, this command specifies the form of pulse.
There are two forms of pulse:

Invert mode is disabled by default.

Example of Pulse Mode

example of pulse mode (normal pulse output)

<?php
$pid = pid_open("/mmap/ht0");               // open HT 0
pid_ioctl($pid, "set div us");              // set unit: microsecond
pid_ioctl($pid, "set mode output pulse");   // set mode: pulse
pid_ioctl($pid, "set count 1 2");           // set count values: 1, 2
pid_ioctl($pid, "set repc 1");              // set repeat count: 1
pid_ioctl($pid, "start");                   // start HT
while(pid_ioctl($pid, "get state"));
pid_close($pid);
?>

Pulse mode basically changes level from low to high. The timing of change depends on both division rate and count values (T1 and T2). The figure below shows waveform of the example above.

ht_set_pulse_02

example of pulse mode (inverted pulse output)

<?php
$pid = pid_open("/mmap/ht0");               // open HT 0
pid_ioctl($pid, "set div us");              // set unit: microsecond
pid_ioctl($pid, "set mode output pulse");   // set mode: pulse
pid_ioctl($pid, "set count 1 2");           // set count values: 1, 2
pid_ioctl($pid, "set repc 1");              // set repeat count: 1
pid_ioctl($pid, "set output invert 1");     // invert output
pid_ioctl($pid, "start");                   // start HT
while(pid_ioctl($pid, "get state"));
pid_close($pid);
?>

After executing the command line "set output invert 1", all output levels are inverted including a pulse output. The figure below shows waveform of the example above.

ht_set_pulse_03