MSP-EXP432E401Y: Read postion und velocity from encoder

Patrick Schneider

Prodigy 80 points

Part Number: MSP-EXP432E401Y
Other Parts Discussed in Thread: SYSCONFIG, MSP432E401Y

Hello TI-Community,

i am trying to get my position and velocity from an encoder. I am using the MSP-EXP432E401Y (TI-RTOS).

The descriptions showed, that I have to use the QEI driverlib (Quadro Encoder Interface).

And the manual defines the relevant ports for Channel A and B are:

Channel A -> PhA0 -> GPIO 82

Channel B -> PhB0 -> GPIO 83

I found the following example (but i dont get it):

https://www.programmersought.com/article/38824307895/

I tried to run it. But i don't understand the example and especially where the ports are defined.

I tried to add the given GPIO Pins in the syscfg-file:

but it throws a warning:
#48-D incompatible redefinition of macro "GPIO_PL1_PHA0" (declared at line 54 of "C:/Users/psc/workspace_v10/gpiointerrupt_MSP_EXP432E401Y_tirtos_ccs/Debug/syscfg/ti_drivers_config.h") .ccsproject /gpiointerrupt_MSP_EXP432E401Y_tirtos_ccs line 284, external location: C:\ti\simplelink_msp432e4_sdk_4_20_00_12\source\ti\devices\msp432e4\driverlib\pin_map.h C/C++ Problem

I am new to the ti products and therefore this question is probably obvious. I still hope that somebody can help me.

A small code snippet and a description would be helpful.

With best regards

Patrick

over 2 years ago

0 Leonardo Estevez over 2 years ago

TI__Genius 12615 points

Hi Patrick,

Unfortunately, we don't have code examples for this interface. According to this thread, the best place to start is the API reference manual:

https://e2e.ti.com/support/microcontrollers/msp430/f/msp-low-power-microcontroller-forum/786958/msp432e401y-ask-for-example-about-ethernet-usb-can-qei-and-epi?ReplyFilter=Answers&ReplySortBy=Answers&ReplySortOrder=Descending

BR,
Leo

0 Patrick Schneider over 2 years ago in reply to Leonardo Estevez

Prodigy 80 points

Hello Leonardo,

I already found that thread in the past.

The mentioned driverLib API guide https://dev.ti.com/tirex/content/simplelink_msp432e4_sdk_2_40_00_11/docs/driverlib/msp432e4/html/group__qei__api.html describes the provided functions.

But nowhere is explained how to configure the ports.

0 Leonardo Estevez over 2 years ago in reply to Patrick Schneider

TI__Genius 12615 points

Hi Patrick,

Port configuration is typically done with a tool called "SysConfig" that can be found here:

https://dev.ti.com/

If you select QEI in this GUI - you'll see a resource conflict for the micro-USB connector on this Launchpad. If you ignore this, you should be able to generate the relevant code as an example.

BR,
Leo

0 Patrick Schneider over 2 years ago in reply to Leonardo Estevez

Prodigy 80 points

Hello Leonardo,

This helped! But i still have problems getting the encoder to work.

I added QEI like this:

and used the api like this from http://software-dl.ti.com/simplelink/esd/simplelink_msp432e4_sdk/4.20.00.12/docs/driverlib/msp432e4/api_guide/html/group__qei__api.html

Just that I changed "QEI_BASE" to "MyQEI" and added the following include:

#include <ti/devices/msp432e4/driverlib/driverlib.h>

But the programm fails with the error: identifier "MyQEI" is undefined.

Is there something else to add or include?

Another try:

QEI0_BASE is defined in msp432e401y.h:

#define QEI0_BASE ((uint32_t)0x4002C000)

When I use the code with "QEI0_BASE" it throws no error... but it still doesn't work.

Do you have any advice?

With best regards

Patrick

0 Patrick Schneider over 2 years ago in reply to Patrick Schneider

Prodigy 80 points

I also tried this:

https://www.programmersought.com/article/38824307895/

It's an example with exactly my microcontroller. It throws no error... but the Interrupt function is never called.

+1 Leonardo Estevez over 2 years ago in reply to Patrick Schneider

TI__Genius 12615 points

Hi Patrick,

I'm not familiar with this interface. I did find several other threads which I believe should have relevant information here:

https://e2e.ti.com/support/microcontrollers/other/f/908/t/872287?keyMatch=QEI&tisearch=Search-EN-everything

https://e2e.ti.com/support/microcontrollers/other/f/908/t/858407?keyMatch=QEI&tisearch=Search-EN-everything

https://e2e.ti.com/support/microcontrollers/other/f/908/t/919892?keyMatch=QEI&tisearch=Search-EN-everything

https://e2e.ti.com/support/microcontrollers/other/f/908/t/927591?keyMatch=QEI&tisearch=Search-EN-everything

Hope this helps.

BR,
Leo

0 Patrick Schneider over 2 years ago in reply to Leonardo Estevez

Prodigy 80 points

Hello Leonardo,

thank you for the quick and helpful response.

Thanks alot, at the end I understood a lot.

It worked :-)

The code and knowledge for anybody who needs it:

From the datasheet:

Therefore:

=> SYSCTL_PERIPH_GPIOL in SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOL);

=> GPIO_PIN_1 | GPIO_PIN_2 in GPIOPinTypeQEI(GPIO_PORTL_BASE, GPIO_PIN_1 | GPIO_PIN_2);

Code:

void read_Encoder(void)
{
// Configure the system clock for 120 MHz
MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480),
120000000);

// Enable QEI Peripherals
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOL); // For PL1 and PL2
SysCtlPeripheralEnable(SYSCTL_PERIPH_QEI0);

//Set Pins to be PHA0 and PHB0
GPIOPinConfigure(GPIO_PL1_PHA0);
GPIOPinConfigure(GPIO_PL2_PHB0);

//Set GPIO pins for QEI. PhA0 -> PL1, PhB0 ->PL2. (See documentation shown in first picture)
GPIOPinTypeQEI(GPIO_PORTL_BASE, GPIO_PIN_1 | GPIO_PIN_2);

//DISable peripheral and int before configuration
QEIDisable(QEI0_BASE);
QEIIntDisable(QEI0_BASE,QEI_INTERROR | QEI_INTDIR | QEI_INTTIMER | QEI_INTINDEX);

// Configure quadrature encoder, use an arbitrary top limit of 1000
QEIConfigure(QEI0_BASE, (QEI_CONFIG_CAPTURE_A_B | QEI_CONFIG_NO_RESET | QEI_CONFIG_QUADRATURE | QEI_CONFIG_NO_SWAP), 3999);

// Enable the quadrature encoder.
QEIEnable(QEI0_BASE);

//Set position to a middle value so we can see if things are working
QEIPositionSet(QEI0_BASE, 500);

// Print position and direction to see the value inc/dec
while (1)
{
printf("Position: %lu \n", QEIPositionGet(QEI0_BASE));
printf("Encoder direction: %d \n", QEIDirectionGet(QEI0_BASE));
SysCtlDelay (10000);
}
}

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MSP-EXP432E401Y: Read postion und velocity from encoder