K66 Beta Test

Not open for further replies.


Staff member
We're going to begin beta testing the MK66FX1M0 chip for a high-end Teensy.

Update: See post #8 for latest status. (special thanks to defragster for keeping #8 updated)

The following people will receive free beta test boards. PJRC will pay for shipping too. For packages outside the USA, you'll need to pay any extra tariff/fee the carrier charges upon delivery.
adrian, adrianfreed, Avenue33, bboyes, Ben, Bill Greiman, blackketter, bperrybap, cartere, christoph, Constantin, Cosford, craiglindley, cyborgv2, Defragster, dgarcia42, Donziboy2, doughboy, duff, Elmue, el_supremo, embedded-creations, Epyon, Experimentalist, fms1961, Frank B, Fyod, GremlinWrangler, happyinmotion, Headroom, HWGuy, jakezimmer, jakorten, JBeale, jbliesener, jimmayhugh, joe_prince, jonr, johnnyfp, Jp3141, Koromix, kpc, kriegsman, KurtE, LAtimes, linuxgeek, macaba, manitou, markonian, Markus_L811, MichaelMeissner, MickMad, mlu, monkeybiscuits, mortonkopf, MuShoo, mxxx, Nantonos, nlecaude, nox771, onehorse, pawelsky, Pedvide, Pensive, pictographer, potatotron, robsoles, stevech, sumotoy, syso2342, teachop, Tectu, tenkai, tetsuo, Theremingenieur, tlb, Tomek, turtle9er, whollender, WMXZ, Wozzy, Xenoamor, xxxajk, yeahtuna

Unfortunately, we can't ship everyone a board right away, so they'll be made in 3 or maybe 4 rounds. Rounds 1 and 2 will be a large (approx 3x3 inch) board with the TQFP version of the chip, with sockets at the intended final form factor (2.4 by 0.7 inch). Round 1 will have 10 boards, shipping next week. Round 2 will add 18 more boards over the next few weeks. Round 3 will be a pre-production run of the actual board with the BGA version of the chip and final power supply circuitry. If we can't make enough on these first 3 rounds, a 4th round might be added.

Everyone on this list has been a regular forum contributor or software developer. Robin and I really appreciate everything you've done. We want to get all of you boards as early as possible. But as a practical limit with so much hand soldering, we need to prioritize. So far, for round 1 we will send to:
Frank B, Theremingenieur, KurtE, dgarcia42, manitou, Defragster, sumotoy, el_supremo

If you'd like to receive a board in round 1 or 2, the magic words are "I do have time for beta testing" and some idea of what things you might try testing. If you're busy, I recommend waiting for round 3, which will have a nice USB host current limit circuit that's not present in rounds 1 & 2. If there are extra boards, we might open up a 4th round and perhaps include people not on the original list.

To receive a beta test board please contact Robin directly at robin at pjrc dot com, especially if your forum email address is not your primary one.

I'd like to ask everyone to please avoid posting photos of the boards, and to keep all conversation on this forum thread. I'm trying to allow openness and access to technical information while avoiding premature promotion & vaporware. Hopefully a text-only forum thread is a good compromise. Please don't post pictures, especially on social networks, until we've finalized a page on the website (with photos) for ordering the final board.
Do not post pictures or mockups of the new Teensy here or anywhere else. Do not post pinout diagrams. Do not post videos. Do not talk/post about the new Teensy on social media sites or news sites. Keep all conversation about the new Teensy in this thread, and keep it text-only.

==>Additional Information in Post #8!

Datasheets K66 (3.3V only):
K66 Data Sheet (electrical specs): http://cache.nxp.com/files/32bit/doc/data_sheet/K66P144M180SF5V2.pdf
K66 Reference Manual (programming specs): http://cache.nxp.com/files/32bit/doc/ref_manual/K66P144M180SF5RMV2.pdf

Datasheets K64 (5V tolerant):
K64 Data Sheet (electrical specs): http://cache.nxp.com/files/microcontrollers/doc/data_sheet/K64P144M120SF5.pdf
K64 Reference Manual (programming specs: http://cache.nxp.com/files/microcontrollers/doc/ref_manual/K64P144M120SF5RM.pdf

Tips for the FPU:
Just wondering if there was a simple fun thing to do with the FPU I came across this with some functional notes:
10 useful tips to using the floating point unit on the ARM® Cortex®-M4 processor
{ and license required Fast FP for ARM and Thumb2: GoFast Floating Point Library - Micro Digital }

Pads/Pins: UPDATED 06/19/16
Outside edge pads (counterclockwise)

Pin  ADC  Ser  PWM  SPI     I2C   CAN  Touch  I2S   Eth   Native
---  ---  ---  ---  ---     ---   ---  -----  ---   ---   ------
0         RX1        MOSI1             TOUCH              B16
1         TX1        MISO1             TOUCH              B17
2              PWM                                        D0
3              PWM          SCL2  TX0         txd0  RXD1  A12
4              PWM          SDA2  RX0         lrclk RXD0  A13
5         tx1  PWM                                        D7
6              PWM   CS1                                  D4
7         RX3  PWM   mosi0  scl0                          D2
8         TX3  PWM   miso0  sda0                          D3
9         RX2  PWM   CS0                      BCLK        C3
10        TX2  PWM   CS0                                  C4
11                   MOSI0                    MCLK        C6
12                   MISO0                                C7
24                                                  CLK   E26
25                                            bclk  RXER  A5
26        tx1                                 txd1  RXDV  A14
27        rx1                                 rxd0  TXEN  A15
28                                            rxd1  TXD0  A16
29             PWM                tx0  TOUCH  bclk        B18
30             PWM                rx0  TOUCH  lrclk       B19
31   A12  RX4                                             B10
32   A13  TX4        SCK1                                 B11

33   A14  TX5               scl0  TX1                     E24
34   A15  RX5               sda0  RX1                     E25
35   A16       PWM                            mclk        C8
36   A17       PWM                                        C9
37   A18       PWM          SCL1                          C10
38   A19       PWM          SDA1              rxd1        C11
39   A20                                      mclk  TXD1  A17
DAC0 A21
DAC1 A22
13                   SCK0                     RXD0        C5
14   A0        PWM   sck0                                 D1
15   A1              CS0               TOUCH  txd1        C0
16   A2                     scl0       TOUCH        MDIO  B0
17   A3                     sda0       TOUCH        MDC   B1
18   A4                     SDA0       TOUCH        TIMER B3
19   A5                     SCL0       TOUCH        TIMER B2
20   A6        PWM   CS0                                  D5
21   A7   rx1  PWM   CS0                                  D6
22   A8        PWM                     TOUCH  TXD0        C1
23   A9        PWM                     TOUCH  LRCLK       C2

Interior pads (same location as Teensy LC & 3.2)

Interior pads (located between pin 27 & 38/A19)

Interior pads (meant for 5 pin header)
Host D-
Host D+

On-board SD card (decicated 4-bit SDIO)
DAT2   (PTE5)
DAT3   (PTE4)
CMD    (PTE3)
CLK    (PTE2)
DAT0   (PTE1)
DAT1   (PTE0)

TBD: extra pads if they fit on bottom side
40        TX6             sca0
41        RX6             scl0
42                        SCL3             lrclk
43                        SDA3             txd0
44                  MISO2
45                  MOSI2
46                  SCK2
47                  CS2

boards.txt for beta testers here: https://forum.pjrc.com/threads/34808-K66-Beta-Test?p=110741&viewfull=1#post110741 (NEW 7/28/16)

The beta test boards use a Mini-USB connector, not Micro-USB.

List of stuff to test: THIS LIST IS OUTDATED, LAST UPDATE 6/18/16!

Edit1: Added K64 Datasheet links
Edit2: spelling
Edit3: Added quote by defragster
Edit4: Added pinout by Paul
Edit5: Changed pinout by Paul to pinout by Frank B with Ports added
Edit6: Pins 3 and 4 are not touch-capable. Added USB pin row and Reset/Program/Vbat row.
Edit7: Add link to boards.txt, add info mini usb
Edit8: Add list of stuff that needs testing
Edit9, 10 11, 12: Update test list
Edit13: Add link to Post#8, add warning about outdated information
Last edited:
Thank you for choosing me. However, please feel free to put me at the back of the bus re: distributions. I am currently very busy with my loggers!

Look forward to the K66!!!
Don't forget to include your user name when you email me. I recognize most of the names, but it does help me out a lot when the info is included. Also, if you are outside the US and are in round 1 or 2, let me know which carrier works best in your country - UPS, Federal Express, or DHL.
Great, I'm looking forward to it (in stage 3), though I probably don't stress the Teensy's like others do. It would be useful at some point to get a final pin assignment list, and a brief spec list of what of the K66 will be brought out, but that can wait until it is closer to announce (I assume we will have the information on the card and/or pcb when it physically arrives).
K66 Sticky Links Semi_Wiki index

Repurposing this post to provide LINKS into what now is almost 800 posts to the current state of T_3.6 Beta hardware notes and library and usage developments. [name:: K66 to be released as Teensy 3.6]

LIVE ON KICKSTARTER :: This project WAS funded on Wed, Sep 7 2016 11:59 PM PDT.

NEWER SHORTER Thread - that may collect other good info : Quick-Links-to-Teensy-3-5-3-6-Git-Libraries . . . with the shipping of the Kickstarter rewards, BETA info here may now grow stale . . .

ALL regular KickStarter rewards are shipping with latest firmware. For those with BETA and EARLY KICKSTARTER units please see this post for into about bootloader update on your device :: LINK to POST

KS Rev of Teensy 3.6 card PDF's.

Teensy 3.6 Analog Reference Card showing pin source

Preliminary Eagle footprint Library For KS Teensy 3.5/3.6, Another Eagle Teensy drawing and Another version Eagle Library - includes prior Teensy 3 and LC

TeensyPinsB.PNGPin Spreadsheet by Ben

See post one and perhaps post three above for added info on working with the Teensy 3.6 K66 board is __MK66FX1M0__. [ corresponding ID for Teensy 3.5 K64 is __MK64FX512__ ]

Some Beta Teensy 3.5 boards were sent out and a new thread started for Features and coverage with that Device: K64-Beta-Test-Teensy-3-5

Essentials - you need TeensyDuino 1.30++ installed:
latest K66/K64 boards.txt included in released 1.30 (Aug18)
On Teensy 3.6 (K66) No pins are 5V tolerant - other than Vin on the T_3.6 [ Teensy 3.5 is 5 volt tolerant on Digital Pins]
CORES Hardware definition on GitHub

Device libraries:
uSDFS :: ported ELM-CHaN's FATFS to K66 as Teensy library (with GitHub link) Post w/details
i2C_t3 :: Updated i2c_t3 library given the recent K66 pin information
Serial# :: K66 has working support for 6 Serial ports - [ Merged in CORES ]
SPI :: Library on GitHub
Wire :: Library on GitHub
UHS30 :: Teensy K66 and USB Host Library version 3.0. [ EXTERMELY ALPHA! ]
ADC :: Updated the ADC library to support Teensy 3.5/3.6(K66) - [github.com/pedvide/ADC]
Snooze :: Working BETA for K66/K64 low power usage
DMASPI :: library updates here
CAN :: Simultaneous Dual CAN

Hardware Adjustments - Bus speed etc:
Modifying F_BUS Speed
ADC VREF selection for K66

Software Samples and Features:

Notes on additional Hardware:

Known Work Items/Issues:
T_3.6 EEPROM WRITE access not valid over 120MHz - needs speed drop from HSRUN mode. - This is one way to do it.

Early Pin notes below are for PROTO (round 1 & 2) Beta boards. The Round 3 boards are ideally the final layout and design. Top primary pins are common - the bottom pins are now set in gold on Round 3 boards and functions should be as documented in this post.

Updated info PROTO_beta board pins:
The 2x5 header on the board just below SDCard pins. From my previous posting about pin numbers with Pauls updated pin definitions, these pins are:
3.3V  [] ()  GND
   48  () ()  47
   57  () ()  56
   51  () ()  52
   53  () ()  55

From this message: ...
Here's an update on the likely extra bottom-side pins. ... probably be a total of 18 bottom side pins ...
Here is a link to extended pin map data and ALT I2C usage - And this may show SDHC details not yet confirmed as exposed by PJRC?
Pin  ADC  Ser  PWM  SPI     I2C   CAN  Touch  I2S   Eth   Native
---  ---  ---  ---  ---     ---   ---  -----  ---   ---   ------
40                                                        D15
41                                                        D11
42                          SDA3              txd0        E10
43                          SCL3              lrclk       E11
 - - - - - - - - - - - - - 
44                  CS2                                   B20
45                  MOSI2                                 B22
46                  MISO2                                 B23
47                  SCK2                                  B21
48        RX6               scl0                          D8
49        TX6               sca0                          D9
50   A23                                            TIMER B4
51   A24                                            TIMER B5

* have an evolving library - make a post and keep it updated in one place - send a link to be 'Sticky' - right click post number and send the URL. *
Feedback?:: PJRC, FrankB, Theremingenieur, KurtE, dgarcia42, manitou, sumotoy, el_supremo, pictographer, WMXZ, duff, bperrybap, nox771, Pedvide, xxxajk, macaba, mxxx, dgarcia42, JBeale, ...

And out go boards for round 3 . . .

Initial post:
Awesome - I sent email to Robin ... Also looking forward to the K66
Last edited:
Put me in on Round 3 or even 4 if that is happening I'm moving again in July :(. Then again in a year, can't wait to be settled! I'm glad to see this becoming reality though!
I'm more than happy to wait, and am honored to be on such a short list with so many talented people.:D
Thank you both for you generosity!
I sadly don't have time to beta test it, so put me on the 3rd or 4th round.
Thank you again!
Thank's for getting the opportunity to test the new K66 board.
yes, I'm very interested and I do have time for testing the K66 for ultrasound data acquisition and processing.
Sounds great! Should be a lot of fun.

I will be curious to try it out with Robot hexapod code base. Earlier I did work to port the code base from fixed based to floating point, but never fully debugged. Maybe gives me a good reason to do so now!

would it be possible to get the schematic and pin description of the sockets?
I'm just revising the pcb of my ADC card, so this information would now be very useful, even if it needs some time for me to receive the board.
If you plan to put this info onto the forum in the next days, I can wait. If you have other plans, maybe you could e-mail the info to the list in post #1.
PJRC you are very generous. Please put me down the list as I don't have time for Beta testing right now. I will email Robin later. Thankyou so much for your great products and awesome technical support.
In case Awesome didn't cover it - Thanks indeed. Does this 'Beta Device' have a usable/official name? Even abbreviating to MostAwesomeFastestT3ppFPU Is too hard to type and probably makes a worse TLA. I suppose more telling questions will have answers this time next week :)

Just wondering if there was a simple fun thing to do with the FPU I came across this with some functional notes:
10 useful tips to using the floating point unit on the ARM® Cortex®-M4 processor
{ and license required Fast FP for ARM and Thumb2: GoFast Floating Point Library - Micro Digital }

<edit> This from the 'Any-Chance-of-a-Teensy-3-1' Thread:
Cortex 4 play with the Freescale FRDM-K64F?
Last edited:
Oh wow, I'm really excited for this one! 180MHz rated... I wonder how far we can push it!

Put me down for a round 3/4 please, I'm truly bogged down in a large project with a lot of K20s at the moment 0.o

Will you be exposing the SWD or JTAG interface for debugging, I know a lot of people really want this option. Also if this is a chance to change the bootloader firmware allowing a long press of the button to trigger a reset would be a great addition

That ethernet controller looks very interesting, the Kinetis SDK has the TCP/IP stack (lwIP) available. We may even be able to make this device appear on a computer network which would be great for smart homes
Last edited:
That ethernet controller looks very interesting, the Kinetis SDK has the TCP/IP stack (lwIP) available. We may even be able to make this device appear on a computer network which would be great for smart homes

Though I suspect that for smart homes, the market has shifted to wi-fi over wired ethernet.

With ESP8266's being fairly cheap for single unit sales (under $2.50 from Chinese sellers, under $5.00 from US sellers), I suspect the ethernet support in the K66 may not be that big of a needed feature (having more spi, i2c, serial ports, more analog pins brought out for easy soldering, higher clock speed, single precision floating point, and 2 DACs are likely more things that bring people in).
Last edited:
Not open for further replies.