Note: A user, Felix, from Germany made a USB host adapter board from blackketter's design for the FRDM4236-V3.  He tested it successfully. He kindly sent us his project with SCH and BOM. With his permission, we post his project here. We appreciate his willingness to help other users very much.  Some users had a hard time to buy the Micro SD. His BOM will tell the source. All parts for the FRDM4236-V3 can be purchased from one company, it can save your time to source the parts and your shipping cost.
 
The newest FRDM4236 breakout board without USB Host is available now.
The newest FRDM4236-V3 breakout board with USB Host is available now.

Check out the newest FRDM4236-V3 info. at the end of this page.
   

 

  
  FRDM4236 - a third Teensy 4.0
breakout board		  

Teensy 4.0 with FRDM4236

  
   

FRDM4236 features:

1. Staggered castellation for 1mm pitch holes, the staggered castellation holes are a bit larger and easier to be soldered without creating a solder bridge to an adjacent hole/pad.

2. Built-in SD card.  When SD is not used, the D34-D39 can be used as I/O pins.

3. All components can be 0805, except C2 can even be 1206, easier for DIY.

4. Self-locking pads for a 128x32 OLED display.
  

5. Teensy 3.6 footprint and breadboard friendly.

6. Low cost, PCB and all parts including two 24x1 male headers  should be < $5.

 

Soldering instructions:

Because this breakout board has 1mm pitch castellated holes, you need to prevent no-clean flux residue trapped around the 1mm pitch holes, especially the final product is made of 2 stacking boards. So if you use non-clean flux, use as little as possible. 
After soldering, flux residue could be conductive especially if board is contaminated. 

1.  These are the parts you need:
 
  1. FB1: 120-150 ohm Ferrite Bead, 0402-0805 (This part is omitted on the new board)
  2.   C1: 0.1UF, 0402-0805
  3.   C2: 10-47UF, 0402-1206
  4.   R1: 22 ohm, 0402-0805
  5.   S1:  Pushbutton Switch
  6.   J1:  24x1 male header, 0.1" pitch
  7.   J2:  24x1 male header, 0.1" pitch
  8. SD1:  Micro SD card slot

 
2. Solder all components, FB1, C1, C2, R1, S1, SD1, on the breakout board. After soldering, If you use water soluble flux, you can wash it with soap, brush it with a tooth brush, rinse it thoroughly and dry it using a heat gun or a hair dryer.
3. Break J2 into 3 pieces, 7x1, 2x1 and 15x1.  Place J1 and 15x1 headers on a breadboard as shown at left. Make sure that the headers are 0.6" apart. Do not need 2x1 and 7x1 headers for the time being.

Place the FRDM4236 over the male headers, right-aligned.  It will leave the 4 left-most pins of J1 uncovered.  This is important.   If you misalign it, it will be difficult to undo after soldering. 

 

 
4. Place your Teensy 4 over the breakout board, left-aligned to the GND pin at low left conner.
Start soldering 4 pins in this order: D3, D13, D12, D17. Solder pins while pressing down two boards. 
5. Once those 4 pins are soldered, check to make sure there is no gap between 2 boards. If there is, you still have a chance to correct.

Then solder D4-D11, D14-D16 pins, install 7x1 header left-aligned, and solder all 7 pins, finally solder all other remaining pins.

After that, you only have an opening for a 2x1 header on D18 and D19.

 

 
6. Try to fit the 2x1 header into the opening, you may need to use a small file to make it narrower, then turn the 2x1 header upside down and solder the pins to both PCBs. It's easier to place the board on a breadboard and solder the pins on Teensy 4.0 first, If you heat the pin a little longer, the solder may flow down to FRDM4236 board. If 2x1 headers are not turned upside down, the plastic rail of the header may block solder flow, or solder may not flow down well. The connection may not be reliable. 

Finally push the plastic rail down.

 
7. It's not difficult to solder all castellated holes. The 1mm pitch holes need to be soldered with a small solder iron tip. Keep pressing the iron tip on pads a little longer and let solder flow, or you will get cold solder joints.  If you use non-clean flux, use as little as possible.  I just used flux from 0.025" solder wire, did not add extra. I did not even clean the board with alcohol.  I just used a napkin to wipe it.  If you need to add flux, just apply a bit on a castellated hole only, do not spread it out to the adjacent holes.  You don't need to make the solder joints look pretty, as long as it makes a good connection you can stop.  After soldering you don't want to leave too much flux residue around 1mm pitch holes and get into hard to clean spots, it may cause contamination and residue becomes conductive. When using alcohol to clean you may spread out residue and contamination to hard to reach spots since this is a two stacking board construction.

This is the result of soldering with non-clean flux on rev. A board.

 
8. This is the result of soldering with water soluble flux on rev. B board. The solder joints look a bit nicer after cleaning with water, but it doesn't make any better in product performance.

If you use water soluble flux, you can wash it with soap, brush it with a tooth brush, brush and rinse it thoroughly and dry it using a heat gun or a hair dryer.  I used a USB fan to blow it for all night and test it on the following day. Just let it sitting to dry overnight may not be good enough to get rid off moisture.  Either use a heat gun for the fast result or a small USB fan to blow it over night.

 
9. Before running a sketch, use a DMM to measure resistance between each pin of D33-D39 to the 3V.  It should be greater than 6 M ohms. Red probe connects to 3V, black probe connects to a pin. If you get a small number, like 10K, your board is contaminated, it won't work. You need to see mega ohms.
Also check there should be no shorts in adjacent pins between D33-D39 which are connected to the 1mm pitch holes. Finally check continuity between 1mm castellated holes and pin 34- pin39.

This test was done on the rev. A board. (I did not clean it after soldering it with the flux just in the solder wire).  If you pass this test, you are all set to use the Teensy 4 with this breakout board.

 

 
10. If you would like to separate power sources, VUSB and Vin. The simplest way is to add a reversing polarity protection diode. 

At first, you need to cut the trace between VUSB and VIN on the solder side.
Then, add a schottky diode.  There is room for adding an 1N5817 schottky diode on the T4.  The pad above the micro USB jack is VUSB, just solder the anode of 1N5817 to the pad, solder the cathode of 1N5817 to the Vin.  After that, you can connect USB power and external VIN at the same time.

 
 

 

Teensy 4.0 with 3.6 footprint on EduBase-V2

Teensy 4.0 SDIO tested OK with
Bill Greiman's SdFat 2.0.0-beta.3

 

 

Defective Oshpark PCB

  
Just received this board from Oshpark a few days ago. I uploaded Gerber files to Oshpark on 9/23/19, and shared a few days before I stopped sharing. I felt that it's not a good idea to share a untested board. Although it was tested OK with the PCB made by a different manufacturer. I think that I made a good decision, otherwise someone could have wasted money because this time the Oshpark board is unusable. 

 
bove is the drilling data file which I specified 15 more castellated holes. The six 1mm-pitch castellated holes were made OK, but other 15 castellated holes were not made. 

If you would like to order this board, you need to send an email to Oshpark and remind them to route out all cut off holes.

 

 
   

FRDM4236 without USB Host  Schematic

 If you order it from Oshpark and you don't have parts on hand, you can try the following:

Short R1 and FB1, Leave C1 and C2 open. Don't solder a Micro SD card slot if you just use D33-D39 as I/O pins.
The adapter may still work for 99% of projects. It's not recommended, but an option for a person who does not have time to get parts. You can solder all parts later.

 

 
 

************************************************************************************************************************************************************************************

FRDM4236-V3 with blackketter's USB Host board
 You need to cut the VUSB trace on Teensy 4.0 for using this V3 board. 

 
 

Top view

  

Bottom view
BOM: 
  2.   C1:   0.1UF, 0402-0805
  3.   C2:  10-47UF, 0402-1206
  4.   R1:  22 ohm, 0402-0805
  5.   S1:  Pushbutton ON/OFF power Switch
  6.   J1:   24x1 male header, 0.1" pitch
  7.   J2:   24x1 male header, 0.1" pitch
      J3:   4X1 female header, 0.1" pitch  for OLED display
  8.   J9:   6X1 female header, 0.1" pitch  for blackketter's USB host card
      D1:  Any 1A schottky diode is OK, size can be SOD123 or SMA, such as MBR120VLSFT3G, or SM5817PL-TP or SS14, SS15, SS16.
  9.          or a 3-pin male header.
  10. SD1:  Micro SD card slot
The ferrite bead, BF1, is removed, because most people won't have it on hand.

Many people have different ideas to use two empty pins, we added two pads on DAC1 and DAC0, so one can hard wire them to any other pins.

The D1 or S2 is located at the up left corner, D1 is the default component, it will serve as a reversing polarity protection diode, a high voltage at Vin won't affect VUSB.  If you know that you will not apply higher voltage at Vin, you can install a SPDT slide switch or a 3-pin male header with a jumper which will serve as a hardware power ON/OFF switch.

 

FRDM4236-V3 PCB for USB Host

FRDM4236-V3  Schematic

 

Soldering instructions:

Cut the trace between Vin and VUSB.

Solder all components, C1, C2, R1, S1, SD1 and D1 on the breakout board.  Do not solder a 6-pin female header next to the D1.  After soldering, If you use water soluble flux, you can wash it with soap, brush it with a tooth brush, rinse it thoroughly and dry it using a heat gun or a hair dryer.

If you use non-clean flux, you can wipe it clean with a napkin.
  1. Break J2 into 4 pieces, 2x1, 5x1, 2x1 and 15x1. Place J1 and 5x2 and15x1 headers on a breadboard as shown at left. Make sure that the headers are 0.6" apart. Do not need 2x1 headers for the time being.
 

 

2. Place the FRDM4236 over male headers, right-aligned.  This is important.  If you misalign it, it will be difficult to undo after soldering. 

 

 
  3. Place your Teensy 4 over the breakout board, left-aligned to the GND pin at low left conner.
Start soldering 4 pins in this order: D12, 3V, D13, G. Solder pins while pressing down two boards. 
 

4. Once those 4 pins are soldered, check to make sure there is no gap between 2 boards. If there is, you still have a chance to correct.
 

5. Then solder D0-D11, D14-D17, D20-D23 pins, and all other pins.

After that, you have an opening for a 2x1 header on D18 and D19, another opening for Vin and GND.

 

 
  6. Try to fit the 2x1 headers into the openings, you may need to use a small file to make it narrower, then turn 2x1 headers upside down and solder the pins to both PCBs. It's easier to place the boards on a breadboard and solder the pins on Teensy 4.0 first, If you heat the pin a little longer, the solder may flow down to FRDM4236 board. If 2x1 headers are not turned upside down, the plastic rail of the header may block solder flow, or solder may not flow down well. The connection may not be reliable.

Finally push the plastic rail down.

Solder a 6-pin female header next to the D1 for blackketter's USB Host board.
     
  7. It's not difficult to solder all castellated holes. The 1mm pitch holes need to be soldered with a small solder iron tip. Keep pressing the iron tip on pads a little longer and let solder flow, or you will get cold solder joints.  If you use non-clean flux, use as little as possible.  I just used flux from 0.025" solder wire, did not add extra. I did not even clean the board with alcohol.  I just used a napkin to wipe it.  If you need to add flux, just apply a bit on a castellated hole only, do not spread it out to the adjacent holes.  You don't need to make the solder joints look pretty, as long as it makes a good connection you can stop.  After soldering you don't want to leave too much flux residue around 1mm pitch holes and get into hard to clean spots, it may cause contamination and residue becomes conductive. When using alcohol to clean you may spread out residue and contamination to hard to reach spots since this is a two stacking board construction.
     
  8. Before running a sketch, use a DMM to measure resistance between each pin of D33-D39 to the 3V. Red probe connects to 3V, black probe connects to a pin.  It should be greater than 6 M ohms. If you get a small number, like 10K, it won't work. You need to see mega ohms.

Also check there should be no shorts in adjacent pins between D33-D39 which are connected to the 1mm pitch holes.  Finally check continuity between 1mm castellated holes and pin 34- pin39.

If you pass this test, you are all set to use the Teensy 4 with this breakout board.