Hi there,
I just started developing using a Teensy last week, and am still very new to this. Lots of excellent info on this forum, everyone, thank you!
Anyways, I am trying to understand the functional relationship between the KL02 and the MK20, and I understand that the KL02 acts as flash storage and flashing agent, but I have a few questions which I haven't seen answered anywhere (yes, i've searched the forum a bit). From what I understand, if EzPort chip select is asserted during the MK20 reset, it will behave like a SPI slave, and more specifically like a SPI EPROM. I also understand that the KL02 is acting as the SPI master, and handles getting the usb data (through the MK20), storing it, flashing it back to the MK20's internal flash, and then resetting with EzPort chip select de-asserted to make it start executing the payload.
However, there are a couple of things which I need cleared up...
Referring to the MK20 reference manual, the pinout table indicates that the EzPort pins are as follows:
EzPort Clock: PORT_A0 (pin 22)
EzPort Data-In: PORT_A1 (pin 23)
EzPort Data-Out: PORT_A2 (pin 24)
EzPort Chip-select: PORT_A4 (pin 26)
However, when referring to the Teensy 3.2 schematic, I see that Chip Select (pin 26) is actually Floating!, and instead PORT_A3 (pin 25) is being used (as chip select, I am assuming...).
This leads me to my first inquiry: How is EzPort chip select pin being asserted if pin 26 is floating in the Teensy 3.2 schematic? Why does this even work!?
Second inquiry: Where did I go wrong in understanding the presented info? Is the schematic wrong? is the reference manual wrong? They can't both be correct, can they?
Third Inquiry: what is this arcane magic happening on USB pin4? If you're sending data out from the KL02's PORT_A6 pin to the MK20's PORT_A1 pin, during a flash, then shouldn't this be toggling usb device direction as the line transitions between high and low states?
Fourth Inquiry: How exactly is the KL02 retrieving the USB data from the MK20..?
If anyone can answer any of these questions, I would greatly appreciate it!
Thanks in advance!
I just started developing using a Teensy last week, and am still very new to this. Lots of excellent info on this forum, everyone, thank you!
Anyways, I am trying to understand the functional relationship between the KL02 and the MK20, and I understand that the KL02 acts as flash storage and flashing agent, but I have a few questions which I haven't seen answered anywhere (yes, i've searched the forum a bit). From what I understand, if EzPort chip select is asserted during the MK20 reset, it will behave like a SPI slave, and more specifically like a SPI EPROM. I also understand that the KL02 is acting as the SPI master, and handles getting the usb data (through the MK20), storing it, flashing it back to the MK20's internal flash, and then resetting with EzPort chip select de-asserted to make it start executing the payload.
However, there are a couple of things which I need cleared up...
Referring to the MK20 reference manual, the pinout table indicates that the EzPort pins are as follows:
EzPort Clock: PORT_A0 (pin 22)
EzPort Data-In: PORT_A1 (pin 23)
EzPort Data-Out: PORT_A2 (pin 24)
EzPort Chip-select: PORT_A4 (pin 26)
However, when referring to the Teensy 3.2 schematic, I see that Chip Select (pin 26) is actually Floating!, and instead PORT_A3 (pin 25) is being used (as chip select, I am assuming...).
This leads me to my first inquiry: How is EzPort chip select pin being asserted if pin 26 is floating in the Teensy 3.2 schematic? Why does this even work!?
Second inquiry: Where did I go wrong in understanding the presented info? Is the schematic wrong? is the reference manual wrong? They can't both be correct, can they?
Third Inquiry: what is this arcane magic happening on USB pin4? If you're sending data out from the KL02's PORT_A6 pin to the MK20's PORT_A1 pin, during a flash, then shouldn't this be toggling usb device direction as the line transitions between high and low states?
Fourth Inquiry: How exactly is the KL02 retrieving the USB data from the MK20..?
If anyone can answer any of these questions, I would greatly appreciate it!
Thanks in advance!
Last edited: