On the Tracker One M8 input what has been done to avoid load dump situations that are common in automotive applications? Is it safe to power the Tracker One with just the 12-volt power supply from the vehicle? The input voltage is 6-30 volts however in automotive applications you can see as much as 60v during load dumps. Are there any TVS or MOV implementations on the hardware?
On the Tracker One, the M8 limit of 30V is because of the rated capacity of the M8 connector. The power supply is rated for use at 90V continuously on the internal B8B-PH connector, and the transient spikes in vehicles are fine on the Tracker One via the M8.
Note that this is not true for every other device; most other devices have a limit of 18V and external protection should be used with the Boron, Electron, E Series, etcâŚ
Thank you for the update. On the E-Series PCB I designed I went through building a protected power supply just for those reasons.
One other question I have is on the Tracker First SOM project. I see that the SOM itself is listed 3.88 - 12V VIN however for the SOM first board project it shows 6 - 18V input. I looked at the schematics on that Tracker First SOM project and I donât see anything that would account for the difference of what the SOM lists as acceptable VIN to what this project shows.
The reason I ask is that I am building a complete PCB to house the SOM and I can only assume that there is no protection built-in for load dumps etc found in automotive applications. When I started to look at building a PSU for it I noticed the difference in VIN between the two docs. Any information on this is much appreciated.
The Tracker SoM is a different situation.
The Tracker SoM has the same bq24195 PMIC as the Electron, E Series, Boron and has the same 18V limit as those devices. It would need the additional protection circuits for vehicle use as well. The SoM first board tutorial just connects VIN directly to the SoM.
The Tracker One/Tracker Carrier board has an additional power supply in front of VIN, which is how it can handle 90V and why the minimum voltage is 6V, higher than the other devices.
What confused me though is that the SOM datasheet shows the voltage range as 3.88 - 12VDC (Below is what I am referring to from the SOM datasheet). This is what threw me off. So you are saying that the SOM itself can handle 18VDC and the VIN listed on the datasheet is not 100% accurate?
From the datasheet of the SOM:
The input voltage range on VIN pin is 3.88VDC to 12VDC. When powering from the VIN pin alone, make sure that the power supply is rated at 10W (for example 5 VDC at 2 Amp). If the power source is unable to meet this requirement, youâll need connect the LiPo battery as well. An additional bulk capacitance of 470uF to 1000uF should be added to the VIN input when the LiPo Battery is disconnected. The amount of capacitance required will depend on the ability of the power supply to deliver peak currents to the cellular modem.
That an error and appears to have been copied from the Electron, E Series, etc⌠On earlier devices the VIN maximum recommended voltage was listed as 12V max. However, itâs always actually been 17V (not 18V, I mis-remembered the value), with an absolute maximum of 22V.
In the recommended operating conditions for the Tracker SoM it is listed correctly as 17.0V, the other mentions of 12V should be changed to 17V.
Oh, I do see the max voltage listed now thank you. I am hoping that when Particle releases the schematics for the Tracker One it shows how you guys built the protection and PSU circuit. I spent a long time perfecting mine and would love to compare and take notes from Particle. Thank you for such quick responses I really appreciate the support.
The Eagle CAD files for the Tracker Carrier Board (Tracker One board) and the Tracker Eval board are in Github tracker-hardware now. I also just added PDF versions of the schematics for those who donât have Eagle installed as well.
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Thank you!
@rickkas7 I am looking for the capacity of the battery included in the Tracker One but I cannot seem to find this information in the datasheet, the product page or the technical documentation. Sorry if I missed it. Can you point me to it or add this information?
I know the dev board comes with a 1800mAH battery but I am not sure if that is the same battery in the tracker one black box.
thanks!
thomas
The Tracker One battery is 2000 mAh.
Itâs not in the initial datasheet because the upgrading the battery was being considered shortly before launch and it was in fact upgraded from the standard 1800 mAh Particle LiPo. The datasheets will be updated shortly with the correct battery information.
Is the documentation still current? Is there a PDF drawing for the Tracker SOM footprint?
Anyone here?
The documentation is current. There isn't directly a PDF of the footprint, but the Eagle CAD version is public in hardware-libraries. The best option is to import that into another tool if you need the footprint for a different design tool.
And to confirm: the center pads are not to be soldered. Can they be excluded from the footprint?
Yes, the center pads should be omitted from your footprint. The public Eagle CAD version has a tRestrict box around where they are so a top trace isn't placed directly under the pads, since the trace would only be protected by its resist.
The datasheet has a schematic starting on p. 31. Is this available in true PDF format (searchable)?
No, the schematic is only available in the low-resolution png file for the Tracker SoM.
The carrier board inside the Tracker One and the Eval board are public, however, and can be found here in Eagle CAD format.
Questions:
- /NRF_RST (pin AC13): does this have an internal pullup on nRF52? I can't see one on the Tracker SOM.
- Is R79 depopulated on all versions of the Tracker SOM?
- If /NRF_RST is asserted, does the Tracker SOM firmware assert reset to all other modules?
- RGB_RED, RGB_GREEN, RGB_BLUE are on nRF52 pins R24 (P1.06), T23 (P1.05) and V23 (P1.03) in the schematic. RGB LEDs in the Block Diagram on p. 5 are connected to pin P0.13, P0.14 and P0.15. Which connections are correct?
- /MODE is connected to P1.13 in the schematic but to P0.11 in the Block Diagram. Which one is correct?
- /NRF_RST (pin AC13): does this have an internal pullup on nRF52? I can't see one on the Tracker SOM.
There is a 100K pull-up in the nRF52 MCU. If using an external button we recommend adding an additional 10K pull-up.
- Is R79 depopulated on all versions of the Tracker SOM?
Yes. On all Tracker SoMs /NRF_RST is connected to the AM1805 /RST line (not /IRQ3).
- If /NRF_RST is asserted, does the Tracker SOM firmware assert reset to all other modules?
No. For example, the cellular modem intentionally does not reset so it can stay connected to cellular and reconnect faster. The power can be removed from the cellular modem through software should the modem become unresponsive.
Some chips like CAN have their hardware reset lines connected to the I/O expander and are hardware reset through software at boot.
- RGB_RED, RGB_GREEN, RGB_BLUE are on nRF52 pins R24 (P1.06), T23 (P1.05) and V23 (P1.03) in the schematic. RGB LEDs in the Block Diagram on p. 5 are connected to pin P0.13, P0.14 and P0.15. Which connections are correct?
Block diagram was wrong. I fixed it.
- /MODE is connected to P1.13 in the schematic but to P0.11 in the Block Diagram. Which one is correct?
Block diagram was wrong. I fixed it.