Added on 10月 01, 2018

The Pet Activity Monitor is a self-contained PCB board inside a plastic casing to make it easy to attach to your pet's collar or use the included collar. This activity monitor features a Renesas Synergy™ Platform S3-series MCU, and multiple Renesas power and analog components.

Related Resources

Related Information

Pet Activity Monitor Reference Design

R7FS3A37A3A01CFM
Synergy™ S3A3 Series MCU

ISL9120
Buck-Boost Power Module

ISL9230
Battery Charger Module

ISL28133
Operational Amplifier



Video Transcript

BALTAZAR MERCADO:

Hi. I'm Baltazar Mercado, product marketing manager here at Renesas Electronics. And today, I'm joined by Michael Quirk, product marketing engineer. And we're going to be talking to you about the pet activity monitor, a demo reference design powered by our S3A3 MCU. How are you doing today, Mike?

MICHAEL QUIRK:

Baltazar, I'm doing really good. Thank you.

BALTAZAR MERCADO:

Excellent. Let's jump right into it.

MICHAEL QUIRK:

OK.

BALTAZAR MERCADO:

So tell me a little bit about the pet activity monitor.

MICHAEL QUIRK:

The pet activity tracks steps and it tracks vocalizations or barks. Today's world, good majority of the pets are actually overweight. By seeing and being able to track this data, you can actually work with your pet to help them getting a healthier state of life.

BALTAZAR MERCADO:

I hear you guys worked really hard on this software.

MICHAEL QUIRK:

Yes, we did we spent a lot of time on the software.

BALTAZAR MERCADO:

So can you tell me, what version of the synergy software package or SSP did you guys use?

MICHAEL QUIRK:

At the time, we used the SSP version 1.4. That was the current release when we started the development.

BALTAZAR MERCADO:

Did you run into any software development issues?

MICHAEL QUIRK:

As a matter of fact, we did. There is a feature of the S3 MCU that we were using or wanted to use, that is the ability to use a high speed oscillator or HOCO to be able to drive the USB clock. The default parameters of that have to be set through a protected register. There was no API call in the current SSP at that time.

BALTAZAR MERCADO:

And how did you guys get around this issue?

MICHAEL QUIRK:

The only way we were able to get around this issue is we communicated this issue to the development team. In that process of their research, they came back and pointed us to a function that was weakly defined and could be overridden by writing a new piece of code using the same function name and the same arguments to be able to clear and set this appropriately. They do plan to implement this in a future release of the SSP.

BALTAZAR MERCADO:

That's excellent to hear, Mike. And now, we're going to take it over to Dan, our senior application engineer, who's going to talk a bit more about our hardware. Dan?

DAN GOODHEW:

Hi, Baltazar.

BALTAZAR MERCADO:

So in your design, you're using button cell batteries. What challenges were considered during the design definition?

DAN GOODHEW:

We decided to use a typical 2032 coin cell battery, as these are readily available. But we quickly realized that the user was going to have to change these out pretty often. To reduce this waste, we decided to go with the rechargeable lithium ion coin cell battery instead. That also saves on cost in the long run.

BALTAZAR MERCADO:

So what other issues were discovered making this choice?

DAN GOODHEW:

The first problem we encountered was that we now needed a charging circuit in our system to charge the batteries safely and to protect the surrounding environment. To do this, we needed a charger with a programmable current, as this low capacity battery needs a low current to charge. We also were looking for something with a pre-charge condition and an end of charge condition. Furthermore, when the user plugs it in the system, they might want to transfer data immediately, even if the battery is depleted.

To solve these issues, we used the ISL9230, as it has a separate power supply line for the system load, as well as for the battery. It also solves all the charging requirements. It also has two LEDs that show the system is plugged in and also if the battery is charging.

BALTAZAR MERCADO:

So let me ask you, Dan, were there any other issues?

DAN GOODHEW:

Yes. There was also a second problem of the input voltage. A CR2032 starts at 3 volts and goes all the way down to 2 volts when depleted, whereas a lithium ion battery starts at 4.2 volts and goes down to 2.6 volts. In the meantime, our system is running on a constant 3 volt supply.

BALTAZAR MERCADO:

With such a run range on the battery and the voltages required for this design, how did you work around this?

DAN GOODHEW:

To fix the issue, we changed the power supply from a boost topology to a buck-boost topology. Using the ISL9120 buck-boost switching regulator, we could then take the higher voltage and buck it down to 3 volts, take the lower voltage and boost it up to 3 volts. And when the battery is right around 3 volts, the ISL9120 can alternate between buck and boost mode, as well as pass the battery voltage directly to the system load, thereby saving the switching losses. The ISL9120 is up to 98% efficient. And even at light loads, it can be over 90% efficient.

BALTAZAR MERCADO:

So let me ask, Dan. What if the user wants to use a standard CR2032?

DAN GOODHEW:

Yes, it is still possible to use a CR2032 by changing the jumpers on the board. The jumpers allow the user to bypass the charging circuit and the ISL9120 is still an excellent choice for the power management. If the user wants to, they can also use a lithium ion battery with a little bit higher capacity. Doesn't actually need to be in a coin cell form factor. However, you will need to change the resistors that set the charger so that the system is safe for that battery.

BALTAZAR MERCADO:

Thank you for that, Dan. And to learn more about the pet activity monitor, please visit this URL. And thank you for joining us.