Building Jaguar A3 board Serial #1 - Comments Thread

[DeuceEFI]

Please put your comments regarding my build here, please

[Dan]

Also determined that the load resistor (R62) that connects between the crystal leads needs to be a 1M Ohm resistor (this resistor is NOT optional).

Can you clarify why the load resistor across your crystal is required? I cant open your BOM on the PC I am on at the moment, so I cant tell what crystal you are using. I assume it is a requirement for the type of crystal you are using?

[Dan]

Ok, now for the actual build:

I will spare you the actual steps, which can be found in the Jaguar Assembly Manual. Pictures will be updated soon in the manual to the actual photos I took during assembly of the first board.

Started the build by installing all of the surface mount IC's on the SMD side of the board using solder paste and my DIY reflow soldering oven (plans can be found in my github repository for the reflow oven).

I have built and tested both power supply circuits and they work as designed.

I have added the components for the MCU and for the USB communications circuits without the optocouplers.

I have added the Check Engine Light (CEL) circuit components (R7 and D1).

I have flashed the MCU with the Serial Monitor program found in the FreeEMS-vanilla libs directory using my DIY TBDML (plans for this can be found in my github repository as well) and the Freescale Special Edition CodeWarrior (actually only installed CodeWarrior to use the HiWave.exe Debugger) to flash the Serial Monitor using the Windows version.

I have been able to upload the FreeEMS-vanilla firmware with the MegaTunix Firmware Loader and verified that MegaTunix can communicate with the MCU.

I have verified that the CEL (Yellow LED) blinks at 0.5 Hz while the MCU is running the FreeEMS firmware.

Great work! CONGRATULATIONS!

I am keen to see the results of your future tests! (ADC protection/filter circuits in particular)

[Fred]

Also determined that the load resistor (R62) that connects between the crystal leads needs to be a 1M Ohm resistor (this resistor is NOT optional).

Can you clarify why the load resistor across your crystal is required? I cant open your BOM on the PC I am on at the moment, so I cant tell what crystal you are using. I assume it is a requirement for the type of crystal you are using?

Could be due to several things. If modA and modB are not correct, it IS required. Otherwise the large crystal may just behave differently to the smaller ones. The CPU specifications talk about what they can and can't drive with the fancy circuitry, maybe this crystal exceeded that.

[Dan]

Could be due to several things. If modA and modB are not correct, it IS required. Otherwise the large crystal may just behave differently to the smaller ones. The CPU specifications talk about what they can and can't drive with the fancy circuitry, maybe this crystal exceeded that.

Hmmmm, this is what I was also thinking.

[DeuceEFI]

Also determined that the load resistor (R62) that connects between the crystal leads needs to be a 1M Ohm resistor (this resistor is NOT optional).

Can you clarify why the load resistor across your crystal is required? I cant open your BOM on the PC I am on at the moment, so I cant tell what crystal you are using. I assume it is a requirement for the type of crystal you are using?

This is due to the crystal that I chose, it requires a 1M ohm load resistor along with the 22pf load capacitors to oscillate.

[DeuceEFI]

This is due to the crystal that I chose, it requires a 1M ohm load resistor along with the 22pf load capacitors to oscillate.

Actually, I just tested this on my A2 board using the same crystal and I removed the 1M Ohm resistor and it worked, so indeed it is optional. I was having an issue where I could program the Serial Monitor on the flash through the BDM but couldn't get the USB comms working and I noticed the CEL wasn't blinking, so I put in the 1M Ohm resistor and it worked.

On the A3 Serial #2 board I build I will leave off the 1M Ohm resistor since it is working on the A2 board without it

[Fred]

Thought so :-)

[Dan]

cool!

[TonyS]

Hey Andy,

Congratulations on the success you've had so far and thanks for providing great information to help future development efforts.

As for the crystal cap values, I might be concerned that 20pF didn't work and 22pF worked. Do you have any larger values you could try to see how much margin you have (maybe determine a "sweet spot" cap value wise for the crystal and layout you have?)?
Also, maybe you could put the board in the freezer and oven (warm not broil : ) and see if it still runs.

Thanks,
Huff