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Snow
04-21-2016, 11:52 AM
Hey guys, I was impatient, bored and decided to attempt removal of badly soldered headers without my replacement station.. In any case, it seems I swiped an SMD component and need to know what to replace it with (if that's no problem). I've got a ton of smd components, just need to know if it's a resistor or cap and its value.

It seems to be the trace leading out of pin 10's pad. Below is a photo, don't mind the mess I haven't gotten around to cleaning it yet.

7011

GremlinWrangler
04-21-2016, 12:02 PM
Working from the schematic here:
https://www.pjrc.com/store/teensy3_audio.html
If it's on pin 10 it should be the pullup resistor. Check if the other end goes the 3.3V to verify. Which should mean if you aren't using the SD card you don't have to replace it.

PaulStoffregen
04-21-2016, 01:11 PM
Even if you are using the SD card, that resistor is only needed if you are also using the SPI pins to communicate with *another* device, like the ILI9341 display or the optional extra memory chip. Even then, it's only purpose is to keep the SD card disabled before for use SD.begin(). You can achieve the same thing with a small edit to software, to configure pin 10 as a logic high (disabled) early in the startup. Usually this can be done at the beginning of setup(). For some rare cases where hardware is initialized in C++ constructors before setup() runs, you may need to edit the actual runtime startup code in mk20dx128.c.

We started adding that resistor to all the SPI interface boards, so no chip ever mistakenly tries to act on communication sent to a different chip, regardless of which order you configure things. Rarely is this ever needed, but in the rare cases where it is, the problems can be really confusing. The resistor eliminates those issues, so you can easily use different (separately developed) software libraries without extra work to carefully consider how they initialize hardware when used together in the same project.