The ESM335X PWM1 and PWM2 support output pulse count function in addition to generating standard PWM signals, and output pulse count work is to generate an interrupt and count each of the outputs of the driver, and counts the pulse set by the user. After the number, the driver automatically stops the PWM output, since there is a certain delay in the system response interrupt, the driver is limited to 5kHz to the highest frequency of the output pulse.
By opening the PWM device ("PWM1:" or "PWM2:"), the application uses the pulse count function, below is the sample code:
#include "stdafx.h"
#include "bsp_drivers.h"
INT _Tmain (int Argc, _tchar * argv [])
{
Handlehpwm;
PWM_INFO PWM_INFO;
DWORDDWBYTES;
Bool brc;
HPWM = CREATEFILE (Text ("PWM1:"),
Generic_read | generic_write,
File_share_read | file_share_write,
NULL,
Open_EXISTING,
FILE_FLAG_RANDOM_ACCESS,
NULL);
PWM_INFO.DWNUM = 0; // PWM output mode
PWM_INFO.DWFREQ = 100000; // Frequency range 1Hz ~ 50MHz
PWM_INFO.DWDUTY = 500; // Tsuioli 50%, unit 0.1%
PWM_INFO.DWPOL = 1; // Polarity
BRC = Writefile (HPWM, & PWM_INFO, SIZEOF (PWM_INFO), & DWBYTES, NULL
PWM_INFO.DWFREQ = 0; // frequency parameter is 0, stop PWM output
BRC = Writefile (HPWM, & PWM_INFO, SIZEOF (PWM_INFO), & DWBYTES, NULL
PWM_INFO.DWNUM = 3; // PWM pulse count output mode
PWM_INFO.DWFREQ = 5000; // Frequency range 1Hz ~ 5kHz
PWM_INFO.DWDUTY = 500; // Tsuioli 50%, unit 0.1%
PWM_INFO.DWPOL = 1; // Polarity, IO remains high when there is no output
// The pulse output is completed or the WriteFile function returns, DWBYTES returns the number of pulses that actually output.
BRC = Writefile (HPWM, & PWM_INFO, SIZEOF (PWM_INFO), & DWBYTES, NULL
CloseHandle (HPWM);
Return 0;
}
PWM_INFO in the above code is used to set the PWM parameter, which is defined as follows:
Typedef struct
{
/ * PWM frequency, unit: Hz, PWM mode output frequency range 1Hz ~ 50MHz, pulse count mode frequency range 1Hz ~ 5kHz
= 0: Stop PWM output * /
DWORDDWFREQ;
DWordDwduty; / * Duty cycle, unit: 0.1%, range: 0 - 1000 * /
DWORD dwpol; / * PWM polarity, = 0: High power is effective, = 1: Low level effective * /
DWORDDWNUM; / * Output pulse number, = 0: Continuous PWM output * /
} PWM_INFO, * PPWM_INFO;
When the parameter sets DWFREQ = 5000, dwduty = 500, dwpol = 1, dwnum = 3, the output waveform is as follows:
Only when the PWM pulse signal is output, the corresponding IO will be driven to a high or low level, and the remaining time PWM pin is a high-resistive input state, because the GPIO pull-up resistor on the ESM335X motherboard is there without pulse When outputting, the PWM pin is a pull-down input state (high). If you actually use, you want PWM to keep it low, you need to increase the reverse in the PWM signal, such as increasing a level of non-door.
Add 1k Euro drop-down resistor on the PWM pin, and set DWPOL = 0, or ensure that the PWM pin is kept low when there is no output, and the picture below adds a drop-down resistor on the PWM pin, and the parameters Set to DWFREQ = 5000, dwduty = 500, dwpol = 0, the waveform output when dwnum = 3:
By using a reverse circuit or an increased pull-down resistor, both methods ensure that the PWM signal remains low during the ESM335X power-on startup process and no pulse output.
The PWM pulse is typically used to control the stepper motor, the pulse frequency determines the motor speed, and the pulse number controls the angular displacement of the motor. Stepping motors In the startup process, it is necessary to control the frequency from a lower frequency to the normal operation of the motor. There is also a corresponding deceleration process when the motor is stopped. When using the ESM335X PWM drive step motor, you can call the WriteFile function multiple times, and then modify the PWM pulse frequency to implement the acceleration and deceleration process of stepper motors. It should be noted that even if the application continuously calls the WriteFile function, there will be several tens to hundreds of microseconds at each call. Read more
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