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USB Low-Full-High Speed Peripherals

gean_3054931
Contributor II

hello,

I have interfaced fx2lp with an image sensor,the frame valid is connected to INT1,image sensor is capable of giving 60frames per second.that is 60 times frame valid interrupt per second,is fx2lp is capable of handling 60 interrupts per second?

correct me if i am wrong.

regards,

geetha.

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1 Solution
SrinathS_16
Moderator
Moderator

Hello Geethanjali,

When an interrupt occurs, the firmware branches to the ISR. Once the code inside the ISR starts executing, the interrupt is disabled and is enabled again only after the RETI instruction which instructs the return of firmware back to the point of interruption. So, depending on the size of the code that is executed inside the ISR, the number of interrupts that can be processed by FX2LP in a particular time varies.

Best regards,

Srinath S

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SrinathS_16
Moderator
Moderator

Hello Geethanjali,

When an interrupt occurs, the firmware branches to the ISR. Once the code inside the ISR starts executing, the interrupt is disabled and is enabled again only after the RETI instruction which instructs the return of firmware back to the point of interruption. So, depending on the size of the code that is executed inside the ISR, the number of interrupts that can be processed by FX2LP in a particular time varies.

Best regards,

Srinath S

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gean_3054931
Contributor II

Hello shrinath,

8051 can handle 60 times of interrupts per second?i.e. can it execute ISR function 60 times per second?

is it capable of doing this regarding hardware and software?

my question is "it will miss interrupts"?,i.e is failed to execute some interrupts within one second?

regards,

geetha.

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SrinathS_16
Moderator
Moderator

Hello Geethanjali,

Whether 8051 will miss interrupts or not depends on the code inside the ISR routine and the time for the instructions to execute.

When the firmware code flow enters the ISR routine, the interrupt gets disabled and is enabled only when the ISR returns back.

Best regards,

Srinath S

gean_3054931
Contributor II

hello shrinath,

isr function contains only 8 bytes data adding to endpoint buffer and switch to manual mode to automode.in this case,is it capable to handle 60 external interrupts per second?

I dont know how much time fx2lp will take to switch from manual mode to automode?

regards,

geetha.

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SrinathS_16
Moderator
Moderator

Hello Geethanjali,

Please refer to the Chapter 12: Instruction Set from the below document EZUSB-TRM.

http://www.cypress.com/file/126446/download

The instruction cycle for each of the EZ-USB instructions has been mentioned in the document. This can be used to calculate the time required for the execution of ISR block in your case. Please note that each instruction cycle is 4 clock cycles in case of EZ-USB. The clock frequency is determined by the CPUCS register setting.

Best regards,

Srinath S