what's the meaning of the callback function

user4337327

Other Parts Discussed in Thread: OMAPL138

Hello all,

I'm learning the EDMA3(used on omapl138)and I was confused when watching the code：

/* Callback function */
void callback(unsigned int tccNum, unsigned int status, void *appData)
{
(void)tccNum;
(void)appData;

if(EDMA3_XFER_COMPLETE == status)
{
/* Transfer completed successfully */
irqRaised = 1;
}

else if(EDMA3_CC_DMA_EVT_MISS == status)
{
/* Transfer resulted in DMA event miss error. */
irqRaised = -1;
}

else if(EDMA3_CC_QDMA_EVT_MISS == status)
{
/* Transfer resulted in QDMA event miss error. */
irqRaised = -2;
}
}

please tell me what's the meaning of this function and how to use it.

over 7 years ago

0 Titusrathinaraj Stalin over 7 years ago

TI__Guru** 116100 points

Which example are you referring ?
Package name and version please.

0 user4337327 over 7 years ago in reply to Titusrathinaraj Stalin

Prodigy 160 points

OMAPL138_StarterWare_1_10_04_01\drivers\edma.c

0 Titusrathinaraj Stalin over 7 years ago in reply to user4337327

TI__Guru** 116100 points

Can you please use the EDMA example ?

Import the below location in CCS and you would get the EDMA example for ARM.
C:\ti\OMAPL138_StarterWare_1_10_04_01\build\armv5\cgt_ccs\omapl138\lcdkOMAPL138\edma

Here, you can see the registration of callback for EDMA.
edmaTest.c
cb_Fxn[tccNum] = &callback; /* Registering Callback Function */

0 user4337327 over 7 years ago in reply to Titusrathinaraj Stalin

Prodigy 160 points

Thanks for your rely,

Maybe I make wrong to express my point.
Actually, I have import the example of the edma.
I just can't understand what's the meaning or purpose of this code(cb_Fxn[tccNum] = &callback; /* Registering Callback Function */)
In other words, I wonder what happened after the callbakc functon.

Meantime, I have another question. I find it seems impossible for me to open some C file when using the EDMA example.
For example, when I want to know what happened after this code( UARTStdioInit(); ), I can only open the file of uartStdio.h.
Can you please tell me how to open the file of uartStdio.c ?

0 Titusrathinaraj Stalin over 7 years ago in reply to user4337327

TI__Guru** 116100 points

It seems checking the status of EDMA transfer state, I hope callback function will be called when the code hit the function "EDMA3EnableTransfer"

For example, when I want to know what happened after this code( UARTStdioInit(); ), I can only open the file of uartStdio.h.
Can you please tell me how to open the file of uartStdio.c ?

Do "Step into" debugging to open and debug the "uartStdio.c" file.
Initially i will ask for the location for "uartStdio.c" and provide the following path to enter the control the "uartStdio.c " file.
C:\ti\OMAPL138_StarterWare_1_10_04_01\utils

0 user4337327 over 7 years ago in reply to Titusrathinaraj Stalin

Prodigy 160 points

Wow, cool !

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what's the meaning of the callback function