source code for Pulse Transit time between ECG and PPG

Divya A N

Other Parts Discussed in Thread: MSP430F5529, ENERGIA, OPT101, ADS1292

Hello everyone,

I had acquired both the ECG and PPG signals. i need to calculate pulse transit time(PTT) between ECG R wave peak and PPG peak. To calculate PTT am using the timer of MSP430F5529 microcontroller. Am setting the threshold value for ECG signal and attaching the interrupt to rising edge of the PPG signal. Timer starts checking for R wave peak of ECG signal, once the R wave peak goes above threshold level, timer should start and simultaneously checks for interrupt. if intrrupt occurs, the timer should stop. the value in timer is converted to milliseconds

Could any please help me to write the source code for PTT calculation in Energia. Am using MSP430F5529 LaunchPad

i had attached the image of PTT calculation

please kindly help

thank you

over 9 years ago

0 Praveen Aroul over 9 years ago

TI__Mastermind 49956 points

Hello Divya,

Which analog front end devices did you use to acquire the ECG and PPG signal?
Unfortunately we do not provide source code support for the implementation of PTT algo.
For MSP430 based implementation, you could direct the questions to MSP430 forum.

0 naveen kumar95 over 9 years ago

Prodigy 20 points

Hi Sir,

Thanks for your reply

I have use OPT101 for acquiring PPG and ADS1292 for acquiring ECG signal.

Could you please help me how do i initialize the timer, start and stop the timer in Energia for MSP430F5529 LaunchPad i.e. i want to count the value in timer

Thank you

0 Divya A N over 9 years ago in reply to naveen kumar95

Prodigy 110 points

Please kindly reply

0 Amy Schnoor over 9 years ago in reply to Divya A N

TI__Mastermind 18285 points

Divya,

This question is better served on the MSP430 forum since it is a question on how to use their processor. You should post the question to their forum.

0 Nazrul Khan over 9 years ago

Prodigy 230 points

hello Divya,
I am also interested to know the algorithm for PTT calculation. Did you get any luck in that respect? Thanks.
Nazrul

0 Nazrul Khan over 9 years ago

Prodigy 230 points

Hello Divaya,
To calculate the PTT, You can consider the following algorithm. Most of the timers(in Microcontrollers), can be programmed as a counter too. And you can program that to generate interrupt at overflow. You can also load the start value in it. That means, if you configure that as a 16 bit counter and if the start/initial value is 0, it will generate interrupt at 65,535(FFFFh). You start the counter from the moment(R wave peak goes above the threshold level). In the corresponding ISR, you keep updating a counter to keep track how many interrupts you got until you reach the peak point at the PPG signal. Once, you arrive at that point, check the counter(how many interrupts, you got during that interval). And the elapsed time(PTT) can be calculated using the following math:

Time elapsed in each interrupt = counter clock period( cycle Time) x 65536
Total elapsed time: Time elapsed in each interrupt x Number of interrupts

I hope that helps you. Regards.

Nazrul