A known good reference board for testing the MKL04 chip when building a DIY Teensy 3.6. Refer to this table for the differences between Teensy 3.6 and other models. The soldering friendly LQFP package (at least more friendly than BGA) is used on this board.

Parts Placement Diagram

Bill Of Materials

1   MK66FX1M0VLQ18
1   IC_MKL04Z32_TQFP32
1   USB A Connector
1   USB Mini B Connector
1   Micro SD Socket
1   MCP1825S Voltage Regulator
1   TPD3S014 USB Power Switch
1   Crystal, 16 MHz
1   Crystal, 32.768 kHz
3   Diode, Schottky, B120
1   Capacitor, 100uF, 6.3V
4   Capacitor, 4.7uF
10  Capacitor, 0.1uF
1   Resistor, 100K
2   Resistor, 470
2   Resistor, 220
2   Resistor, 33
1   Pushbutton
2   Test Point, Black

Bootloader Chip

USB Interruptor

This simple board plugs inline with a USB cable. It always passes the 5V power and normally passes the USB data signals. But when you press the button, the signals are momentarily disconnected.

Why would anyone want or need such a things? Well, for the last few months I’ve been developing a USB Host Library for powerful but complex EHCI USB port in Teensy 3.6. After several false starts and re-reading the USB 2.0 and EHCI 1.0 specs and datasheet over and over (did I mention this 480 Mbit/sec USB host port is powerful but really complex), it’s finally starting to come together.

Now I’m at the stage where it’s time to begin work on code to handle USB disconnect events. When you unplug the cable, the ECHI work queues need to be removed, periodic schedule bandwidth allocation/planning needs to be undone, memory needs to be freed (hopefully it’s all findable from linked lists), hub/port status needs to be updated, and probably a ton of other stuff needs to happen that I haven’t even considered yet…

Reaching over to physically unplug the USB cable gets old quickly! Really, really old, both hands off my keyboard… right when trying to focus. With 12 Mbit/sec USB ordinary switches can usually work, but this is 480 Mbit/sec and I’m already running it through a USB protocol analyzer and a few cables plugged in tandem, leaving not much signal quality margin left. So I made this handy little board with a proper USB 2.0 high speed mux chip. The control signal is just 3.3V logic, so I might even wire it up to something to automate the process.

Admittedly, not many people develop USB host drivers and software stacks (it’s turning out to be probably the toughest coding I’ve ever done), so this little board might not have really wide applications. But here’s all the details anyway. ;-)

Update: check out this similar board, using slightly different parts.

Parts Placement

Bill Of Materials

1   Resistor, 10K, 805              RHM10.0KCHCT-ND
1   Capacitor, 0.1uF, 805           478-1395-1-ND
3   Capacitor, 1uF, 805             587-1281-1-ND
1   Diode, Schottky, B120           B120-E3/5ATGICT-ND
1   MCP1700 3.3V regulator          MCP1700T3302ETTCT-ND
1   FSUSB30 USB Mux Switch          FSUSB30MUXCT-ND
1   USB Connector, Mini-B           609-4701-1-ND
1   USB Connector, Std A            ED90065-ND
1   Pushbutton                      P8016S-ND

How to use Digikey’s website to find alternate parts when any of these aren’t in stock.

Why bother using huge standard size SD cards with a small Micro SD socket? Mostly for testing the SD library compatibility ancient SD cards (which are mostly the large size) on Teensy 3.5 & 3.6.

Who knows, maybe someone else will find this useful for some off-beat application?

The SD socket is Digikey part number HR845CT-ND.

Ethernet Shield for Teensy 3.5 and 3.6.

See this Kickstarter update for more info.

Please understand this shield has very limited software support at this time. However, Manitou’s early benchmarks show excellent performance we can someday hope to achieve as the software matures.

Bill of Materials

Qty  Part                               Digikey
---  ----                               -------
1    LAN8720A                           LAN8720A-CP-CT-ND
1    CAT811T                            CAT811TTBI-GT3OSCT-ND
1    Crystal, 25 MHz                    535-13419-1-ND
1    Transformer, Pulse H1102FNL        553-2204-1-ND
1    Connector, RJ45                    A102068CT-ND
1    Capacitor, 1nF, 2000V              709-1036-1-ND
2    Capacitor, 33pF                    490-5936-1-ND
1    Capacitor, 470pF                   490-1297-1-ND
3    Capacitor, 10nF                    445-1260-1-ND
1    Capacitor, 22nF                    490-8022-1-ND
3    Capacitor, 1uF                     399-5090-1-ND
1    Resistor, 33, 1%                   311-33.0LRCT-ND
4    Resistor, 49.9, 1%                 RMCF0402FT49R9CT-ND
4    Resistor, 75, 1%                   RHM75.0HCT-ND
2    Resistor, 330, 1%                  311-330LRCT-ND
1    Resistor, 1.5K, 1%                 311-1.50KLRCT-ND
2    Resistor, 12.1K, 1%                P12.1KLCT-ND
1    Inductor, Ferrite bead             553-2387-1-ND
2    LED, Green                         475-1410-1-ND

How to use Digikey’s website to find alternate parts when any of these aren’t in stock.

Parts Placement Diagram

Warning: you must solder the LAN8720A’s center pad. This chip will not work if only the outside 24 pins are connected.

A future version of this board may include Power Over Ethernet support…..

This little board fit into a SD socket. The other end is meant to have a connector, Digikey part number 609-1788-1-ND.