Pins to bring out on a hypothetical larger Teensy4

[PaulStoffregen]

While we wait for the amazing 1170 chip, I'm considering making another Teensy4 with the same 1062 chip we have on Teensy 4.0, but in the Teensy 3.6 form factor.

So let's talk in this thread of which pins to (hypothetically) make available.

We would get 18 more pins on the outside edge, and maybe more on the bottom. Very likely the first 10 should be the same pins as we have on the bottom of Teensy 4.0? That would allow only 8 more pins. Or maybe all 18 could be chosen for this board. Only the 28 pins matching Teensy 4.0 have to be preserved.

These are all the unconnected pins on Teensy 4.0 which could become available:

Name      BGA  Analog   ATL0            ALT1            ALT2            ALT3            ALT4            ALT5            ALT6            ALT7            ALT8            ALT9
----      ---  ------   ----            ----            ----            ----            ----            ----            ----            ----            ----            ----
AD_B0_00  M14           PWM2_A3         XBAR_INOUT14    REF_CLK_32K     USB_OTG2_ID     I2C1_SCLS       GPIO1:0         USDHC1_RESET_B  SPI3_SCK
AD_B0_01  H10           PWM2_B3         XBAR_INOUT15    REF_CLK_24M     USB_OTG1_ID     I2C1_SDAS       GPIO1:1         EWM_OUT_B       SPI3_MOSI
AD_B0_14  H14  A1:3     USB_OTG2_OC     XBAR_IN24       UART1_CTS       ENET1588_OUT0   CSI_VSYNC       GPIO1:14        CAN2_TX         wdog1_any       FLEXCAN3_TX
AD_B0_15  L10  A1:4     USB_OTG2_PWR    XBAR_IN25       UART1_RTS       ENET1588_IN0    CSI_HSYNC       GPIO1:15        CAN2_RX         WDOG1_RST_B_DEB FLEXCAN3_RX
AD_B1_04  L12  A1:9     FLEXSPI_B_DATA3 ENET_MDC        UART3_CTS       SPDIF_SR_CLK    CSI_PIXCLK      GPIO1:20        USDHC2_DATA0    KPP_ROW5        GPT2_CAPTURE2   FlexIO3:4
AD_B1_05  K12  A1:10    FLEXSPI_B_DATA2 ENET_MDIO       UART3_RTS       SPDIF_OUT       CSI_MCLK        GPIO1:21        USDHC2_DATA1    KPP_COL5        GPT2_COMPARE1   FlexIO3:5
AD_B1_12  H12  A2:1     FLEXSPI_A_DATA1 ACMP_OUT00      SPI3_PCS0       SAI1_RX0        CSI_DATA05      GPIO1:28        USDHC2_DATA4    KPP_ROW1        ENET21588_OUT2  FlexIO3:12
AD_B1_13  H11  A2:2     FLEXSPI_A_DATA0 ACMP_OUT01      SPI3_MISO       SAI1_TX0        CSI_DATA04      GPIO1:29        USDHC2_DATA5    KPP_COL1        ENET21588_IN2   FlexIO3:13

Name      BGA  ATL0             ALT1            ALT2            ALT3            ALT4            ALT5            ALT6            ALT7            ALT8            ALT9
----      ---  ----             ----            ----            ----            ----            ----            ----            ----            ----            ----
B0_04     C8   LCD_DATA00       QTIMER2_TIMER1  I2C2_SCL        ARM_TRACE0      FlexIO2:4       GPIO2:4         SRC_BOOT_CFG00                  ENET2_TDATA03
B0_05     B8   LCD_DATA01       QTIMER2_TIMER2  I2C2_SDA        ARM_TRACE1      FlexIO2:5       GPIO2:5         SRC_BOOT_CFG01                  ENET2_TDATA02
B0_06     A8   LCD_DATA02       QTIMER3_TIMER0  PWM2_A0         ARM_TRACE2      FlexIO2:6       GPIO2:6         SRC_BOOT_CFG02                  ENET2_RX_CLK
B0_07     A9   LCD_DATA03       QTIMER3_TIMER1  PWM2_B0         ARM_TRACE3      FlexIO2:7       GPIO2:7         SRC_BOOT_CFG03                  ENET2_TX_ER
B0_08     B9   LCD_DATA04       QTIMER3_TIMER2  PWM2_A1         UART3_TX        FlexIO2:8       GPIO2:8         SRC_BOOT_CFG04                  ENET2_RDATA03
B0_09     C9   LCD_DATA05       QTIMER4_TIMER0  PWM2_B1         UART3_RX        FlexIO2:9       GPIO2:9         SRC_BOOT_CFG05                  ENET2_RDATA02
B0_14     E10  LCD_DATA10       XBAR_INOUT12    ARM_CM7_EVENT0  SAI1_RX_SYNC    FlexIO2:14      GPIO2:14        SRC_BOOT_CFG10                  ENET2_TX_EN
B0_15     E11  LCD_DATA11       XBAR_INOUT13    ARM_CM7_EVENT1  SAI1_RX_BCLK    FlexIO2:15      GPIO2:15        SRC_BOOT_CFG11                  ENET2_TX_CLK    ENET2_REF_CLK2
B1_02     C11  LCD_DATA14       XBAR_INOUT16    SPI4_CS2        SAI1_TX_BCLK    FlexIO2:18      GPIO2:18        PWM2_A3                         ENET2_RDATA01   FlexIO3:18
B1_03     D11  LCD_DATA15       XBAR_INOUT17    SPI4_CS1        SAI1_TX_SYNC    FlexIO2:19      GPIO2:19        PWM2_B3                         ENET2_RX_EN     FlexIO3:19
B1_04     E12  LCD_DATA16       SPI4_CS0        CSI_DATA15      ENET_RX_DATA0   FlexIO2:20      GPIO2:20        -               -               GPT1_CLK        FlexIO3:20
B1_05     D12  LCD_DATA17       SPI4_MISO       CSI_DATA14      ENET_RX_DATA1   FlexIO2:21      GPIO2:21        -               -               GPT1_CAPTURE1   FlexIO3:21
B1_06     C12  LCD_DATA18       SPI4_MOSI       CSI_DATA13      ENET_RX_EN      FlexIO2:22      GPIO2:22        -               -               GPT1_CAPTURE2   FlexIO3:22
B1_07     B12  LCD_DATA19       SPI4_SCK        CSI_DATA12      ENET_TX_DATA0   FlexIO2:23      GPIO2:23        -               -               GPT1_COMPARE1   FlexIO3:23
B1_08     A12  LCD_DATA20       QTIMER1_TIMER3  CSI_DATA11      ENET_TX_DATA1   FlexIO2:24      GPIO2:24        CAN2_TX         -               GPT1_COMPARE2   FlexIO3:24
B1_09     A13  LCD_DATA21       QTIMER2_TIMER3  CSI_DATA10      ENET_TX_EN      FlexIO2:25      GPIO2:25        CAN2_RX         -               GPT1_COMPARE3   FlexIO3:25
B1_10     B13  LCD_DATA22       QTIMER3_TIMER3  CSI_DATA00      ENET_TX_CLK     FlexIO2:26      GPIO2:26        ENET_REF_CLK    -                               FlexIO3:26
B1_11     C13  LCD_DATA23       QTIMER4_TIMER3  CSI_DATA01      ENET_RX_ER      FlexIO2:27      GPIO2:27        SPI4_CS3        -                               FlexIO3:27
B1_12     D13  -                UART5_TX        CSI_PIXCLK      ENET1588_IN0    FlexIO2:28      GPIO2:28        USDHC1_CD_B     -                               FlexIO3:28
B1_13     D14  WDOG1_B          UART5_RX        CSI_VSYNC       ENET1588_OUT0   FlexIO2:29      GPIO2:29        USDHC1_WP       -               SEMC_DQS4       FlexIO3:29
B1_14     C14  ENET_MDC         PWM4_A2         CSI_HSYNC       XBAR_IN02       FlexIO2:30      GPIO2:30        USDHC1_VSELECT  -               ENET2_TDATA00   FlexIO3:30
B1_15     B14  ENET_MDIO        PWM4_A3         CSI_MCLK        XBAR_IN03       FlexIO2:31      GPIO2:31        USDHC1_RESET_B  -               ENET2_TDATA01   FlexIO3:31

Name      BGA  ATL0             ALT1            ALT2            ALT3            ALT4            ALT5            ALT6            ALT7            ALT8            ALT9
----      ---  ----             ----            ----            ----            ----            ----            ----            ----            ----            ----
EMC_00    E3   SEMC_DATA00      PWM4_A0         SPI2_SCK        XBAR_IN02       FlexIO1:0       GPIO4:0         USB_PHY1_TSTI_TX_LS_MODE
EMC_02    F4   SEMC_DATA02      PWM4_A1         SPI2_MOSI       XBAR_INOUT04    FlexIO1:2       GPIO4:2         USB_PHY1_TSTI_TX_DN
EMC_03    G4   SEMC_DATA03      PWM4_B1         SPI2_MISO       XBAR_INOUT05    FlexIO1:3       GPIO4:3         USB_PHY1_TSTO_RX_SQUELCH
EMC_09    C2   SEMC_ADDR00      PWM2_B1         SAI2_RX_SYNC    CAN2_TX         FlexIO1:9       GPIO4:9         USB_PHY1_TSTI_TX_EN
EMC_10    G1   SEMC_ADDR01      PWM2_A2         SAI2_RX_BCLK    CAN2_RX         FlexIO1:10      GPIO4:10        USB_PHY1_TSTI_TX_HIZ            FLEXSPI2_B_SS0_B
EMC_11    G3   SEMC_ADDR02      PWM2_B2         I2C4_SDA        USDHC2_RESET_B  FlexIO1:11      GPIO4:11        USB_PHY2_TSTO_RX_HS_RXD         FLEXSPI2_B_DQS
EMC_12    H1   SEMC_ADDR03      XBAR_IN24       I2C4_SCL        USDHC1_WP       PWM1_A3         GPIO4:12        USB_PHY1_TSTO_PLL_CLK20DIV      FLEXSPI2_B_SCLK
EMC_13    A6   SEMC_ADDR04      XBAR_IN25       UART3_TX        MQS_RIGHT       PWM1_B3         GPIO4:13        USB_PHY2_TSTO_PLL_CLK20DIV      FLEXSPI2_B_DATA00
EMC_14    B6   SEMC_ADDR05      XBAR_INOUT19    UART3_RX        MQS_LEFT        SPI2_CS1        GPIO4:14        USB_PHY2_TSTO_RX_SQUELCH        FLEXSPI2_B_DATA01
EMC_15    B1   SEMC_ADDR06      XBAR_IN20       UART3_CTS       SPDIF_OUT       QTIMER3_TIMER0  GPIO4:15        USB_PHY2_TSTO_RX_DISCON_DET     FLEXSPI2_B_DATA02
EMC_16    A5   SEMC_ADDR07      XBAR_IN21       UART3_RTS       SPDIF_IN        QTIMER3_TIMER1  GPIO4:16                                        FLEXSPI2_B_DATA03
EMC_17    A4   SEMC_ADDR08      PWM4_A3         UART4_CTS       CAN1_TX         QTIMER3_TIMER2  GPIO4:17
EMC_18    B2   SEMC_ADDR09      PWM4_B3         UART4_RTS       CAN1_RX         QTIMER3_TIMER3  GPIO4:18        SNVS_VIO_5_CTL
EMC_19    B4   SEMC_ADDR11      PWM2_A3         UART4_TX        ENET_RX_DATA1   QTIMER2_TIMER0  GPIO4:19        SNVS_VIO_5_B
EMC_20    A3   SEMC_ADDR12      PWM2_B3         UART4_RX        ENET_RX_DATA0   QTIMER2_TIMER1  GPIO4:20
EMC_21    C1   SEMC_BA0         PWM3_A3         I2C3_SDA        ENET_TX_DATA1   QTIMER2_TIMER2  GPIO4:21
EMC_22    F1   SEMC_BA1         PWM3_B3         I2C3_SCL        ENET_TX_DATA0   QTIMER2_TIMER3  GPIO4:22                                        FLEXSPI2_A_SS1_B
EMC_23    G2   SEMC_ADDR10      PWM1_A0         UART5_TX        ENET_RX_EN      GPT1_CAPTURE2   GPIO4:23                                        FLEXSPI2_A_DQS
EMC_24    D3   SEMC_CAS         PWM1_B0         UART5_RX        ENET_TX_EN      GPT1_CAPTURE1   GPIO4:24                                        FLEXSPI2_A_SS0_B
EMC_25    D2   SEMC_RAS         PWM1_A1         UART6_TX        ENET_TX_CLK     ENET_REF_CLK    GPIO4:25                                        FLEXSPI2_A_SCLK
EMC_26    B3   SEMC_CLK         PWM1_B1         UART6_RX        ENET_RX_ER      FlexIO1:12      GPIO4:26                                        FLEXSPI2_A_DATA00
EMC_27    A2   SEMC_CKE         PWM1_A2         UART5_RTS       SPI1_SCK        FlexIO1:13      GPIO4:27                                        FLEXSPI2_A_DATA01
EMC_28    D1   SEMC_WE          PWM1_B2         UART5_CTS       SPI1_MOSI       FlexIO1:14      GPIO4:28                                        FLEXSPI2_A_DATA02
EMC_29    E1   SEMC_CS0         PWM3_A0         UART6_RTS       SPI1_MISO       FlexIO1:15      GPIO4:29                                        FLEXSPI2_A_DATA03
EMC_30    C6   SEMC_DATA08      PWM3_B0         UART6_CTS       SPI1_CS0        CSI_DATA23      GPIO4:30                                        ENET2_TDATA00
EMC_33    C4   SEMC_DATA11      PWM3_A2         USDHC1_RESET_B  SAI3_RX_DATA    CSI_DATA20      GPIO3:19                                        ENET2_TX_CLK    ENET2_REF_CLK2
EMC_34    D4   SEMC_DATA12      PWM3_B2         USDHC1_VSELECT  SAI3_RX_SYNC    CSI_DATA19      GPIO3:20                                        ENET2_RX_ER
EMC_35    E5   SEMC_DATA13      XBAR_INOUT18    GPT1_COMPARE1   SAI3_RX_BCLK    CSI_DATA18      GPIO3:21        USDHC1_CD_B                     ENET2_RDATA00
EMC_38    D6   SEMC_DM1         PWM1_A3         UART8_TX        SAI3_TX_BCLK    CSI_FIELD       GPIO3:24        USDHC2_VSELECT                  ENET2_MDC
EMC_39    B7   SEMC_DQS         PWM1_B3         UART8_RX        SAI3_TX_SYNC    WDOG1_B         GPIO3:25        USDHC2_CD_B                     ENET2_MDIO      SEMC_DQS4
EMC_40    A7   SEMC_RDY         GPT2_CAPTURE2   SPI1_CS2        USB_OTG2_OC     ENET_MDC        GPIO3:26        USDHC2_RESET_B                                  SEMC_CLK5
EMC_41    C7   SEMC_CSX0        GPT2_CAPTURE1   SPI1_CS3        USB_OTG2_PWR    ENET_MDIO       GPIO3:27        USDHC1_VSELECT

Name      BGA  ATL0             ALT1            ALT2            ALT3            ALT4            ALT5            ALT6            ALT7            ALT8            ALT9
----      ---  ----             ----            ----            ----            ----            ----            ----            ----            ----            ----
SD_B1_00  L5   USDHC2_DATA3     FLEXSPI_B_DATA3 PWM1_A3         SAI1_TX3_RX1    UART4_TX        GPIO3:0                                         SAI3_RX_DATA
SD_B1_01  M5   USDHC2_DATA2     FLEXSPI_B_DATA2 PWM1_B3         SAI1_TX2_RX2    UART4_RX        GPIO3:1                                         SAI3_TX_DATA
SD_B1_02  M3   USDHC2_DATA1     FLEXSPI_B_DATA1 PWM2_A3         SAI1_TX1_RX3    CAN1_TX         GPIO3:2         CCM_WAIT                        SAI3_TX_SYNC
SD_B1_03  M4   USDHC2_DATA0     FLEXSPI_B_DATA0 PWM2_B3         SAI1_MCLK       CAN1_RX         GPIO3:3         CCM_PMIC_READY                  SAI3_TX_BCLK
SD_B1_04  P2   USDHC2_CLK       FLEXSPI_B_SCLK  I2C1_SCL        SAI1_RX_SYNC    FLEXSPI_A_SS1_B GPIO3:4         CCM_STOP                        SAI3_MCLK

I am considering putting an ethernet PHY chip on this board, with 6 pins/pads to connect another board having the magnetics and RJ45 connector. Or if a PHY chip isn't used, perhaps a high density connector with the RMII signals? Either way, I'm leaning towards reserving B1_04 to B1_11, and B1_14 & B1_15 for native ethernet.

Another feature I'm considering is using the bottom side for locations to add 1 or 2 QSPI memory chips, which could be either flash or psram. If that is done, pins EMC_22 to EMC_29 would likely be used. An alternative would be EMC_10 to EMC16, which supports only a single memory chip (only 1 chip select).

I know JTAG is going to come up. Let me say right now, access to JTAG signals will *not* happen for this board (if this board is even made). Please don't fill this thread with talk of JTAG debug. Yes, I know so many people have strong feelings about this. I do have long-term plans there. But this board, if it gets made, is meant to be a "quick" design that mostly leverages all the work that's gone into Teensy 4.0, to give access to pins & peripherals we couldn't get from Teensy 4.0's small form factor. That means no changes to the bootloader or programming approach. Changing any of that would almost certainly cause developing this board to drag on and on, pulling engineering time away from 1170 next year. So no JTAG.

Please remember this thread is about what pins (from this list) to bring out, and possibly what relatively small & low-risk peripheral hardware might fit nicely in the extra space we get.

[WMXZ]

sdio-uSD socket (sensu T3.6)?

[defragster]

> Emulating T_3.6 presentation of USB_Host connect pins/parts? - that eats board space.
> was going to suggest Qwiic takeoff to add missing things - but I don't see a DAC on i2c.
> make sure it has at least as much clear room to fit a heat sink as T_4.0
--
> Assuming Serial8 will be on the list?
> Do any of the missing pins offer good ALT function for other currently shared pins - like UARTS or SPI?

When the 1170 arrives would it ideally have the same pin mapping and functional parts?
>> 1170 has a single DAC to reserve a space for with similar ALT function pin from 1062
>> Anything else needed for smooth transition?

[MichaelMeissner]

One thought that I've had is instead of a SD card, make the extra space beyond the current Teensy 4 have through hole pins, grouped logically, grouping the pins either into 10 rows of 7 columns each, or 7 columns of 10 rows. Given the SD needs 8 pins, lets say for the sake of argument, you have 7 columns of 10 rows.

You might then have:

• One row for bringing out the micro SD card/third SPI port in the existing Teensy 4.0;
• One row with the standard 5 pins for bringing out the USB header (and maybe use the extra pins for power options);
• One row for the AD_B[01] pins;
• I don't know enough about the others, but the B[01] pins would need 3 rows of 10 pins to bring all of them out;
• But at least the first 10 pins might be enough to bring out the ethernet pins -- if you need LCD, that would need all of the pins;
• No idea about the EMC pins.

Alternatively use the same format as the T 3.6 so people can bring out the pins with things like loglow's shields, even if the pins have different meanings.

[blackketter]

I'm only really missing one specific pin from the Teensy 4.0: RESET

Apart from that, I'd really love to be able to attach inexpensive LCD displays and take advantage of the 2D graphics capabilities and avoid having to funnel through an SPI interface, ideally a 24-bit RGB interface. I realize that this might be a stretch given the pin count requirements.

[vjmuzik]

The pins I would like to see is definitely Serial8, usb host port like a T3.6 offers, and I would love native Ethernet if it’s a possibility. To coincide with the native Ethernet I would like the option of adding an extra ram chip like you were thinking about so that supporting Ethernet doesn’t have to use up a lot of the built in fast memory.

[firehopper]

we have had people ask for concurrent port pins. port0-7 and 8-15 to be able to do faster I/O dont know of thats possible but I'm sure some people would love to have this.

[PaulStoffregen]

we have had people ask for concurrent port pins. port0-7 and 8-15 to be able to do faster I/O

The GPIO registers in these newer chips do not support 8 or 16 bit access.

However, having 8 or 16 consecutive bits of a FlexIO peripheral might be useful...

[PaulStoffregen]

I'm only really missing one specific pin from the Teensy 4.0: RESET

Sorry. Like JTAG, the RESET pin is off limits without a major (1170 delaying) change to the bootloader and programming process.

[blackketter]

Sorry. Like JTAG, the RESET pin is off limits without a major (1170 delaying) change to the bootloader and programming process.

Ah, I see from the schematic that the POR_B pin is used by the boot loader chip. Would it be feasible to add a pin that forced a reset by disabling the 3.3v regulator?

[PaulStoffregen]

I started exploring how the extra space might be used. Here's a quick concept drawing, with the added parts highlighted.



Switching to the larger 12mm chip (necessary for escaping more signals with an affordable PCB) and adding a USB host stuff (highlighted yellow) and SD socket similar to Teensy 3.6 uses up nearly all the space. I guess that's not too surprising, since Teensy 3.6 has a 13mm chip and not much room left over.

At first it seemed impossible to fit an ethernet PHY and a connector. The 4mm LAN8720 chip I've used before just can't fit, unless the connector is extremely small (and fragile). Then I discovered Texas Instruments has a relatively new PHY chip that squeezes the PHY into only 3mm, using a rather strange QFN package. That allows a 2mm pitch through-hole header for the ethernet signals.

One downside to the ethernet PHY chips is about 1 to 2 mA current in their lowest possible power down modes. Of course we'll still support the power on/off feature which will also shut off all power to the PHY.

Which signals to assign to pins 34-41 is still a wide open decision. AD_B1_04, AD_B1_05, AD_B1_12, AD_B1_13 seem like reasonable candidates. That would give 16 bits of a port (though how useful that really is with the GPIO supporting only 32 bit access is questionable) and would also give 16 signals for FlexIO3 (perhaps much more useful). But those 4 pins are sort of lackluster in peripheral features, which is the reason they weren't included in the Teensy 4.0 pinout.

Signals B1_12 & B1_13 would give us access to the last serial port (UART5). Or EMC_23 & EMC_24 could as well, if those signals are used for a place to add a memory chip (which would be on the bottom side - pads similar to the bottom side of the audio shield, but FlexSPI so the memory chip gets mapped into the ARM address space).

This is all very tentative. Now is the time for feedback!

[WMXZ]

This is all very tentative. Now is the time for feedback!

If you succeed with routing, that would be a great solution. I'm with it.

[WMXZ]

Would it be feasible to add a pin that forced a reset by disabling the 3.3v regulator?

is not PMIC_ON_REQ enabling the LDO?

[mjs513]

Signals B1_12 & B1_13 would give us access to the last serial port (UART5). Or EMC_23 & EMC_24 could as well, if those signals are used for a place to add a memory chip (which would be on the bottom side - pads similar to the bottom side of the audio shield, but FlexSPI so the memory chip gets mapped into the ARM address space).

Think going the route of adding a memory chip on the bottom side would be a good idea.

Good luck on the routing.

[vjmuzik]

Looks good so far, looking forward to buying this and getting native Ethernet working, I think it makes the most sense to bring out UART5 and the rest of a 16 bit port. I plan on doing some things that require port access so it would be a nice bonus if it’s possible, for people who really need low power and don’t need Ethernet maybe consider making it easy to cut the power wire running to it.

[MichaelMeissner]

I started exploring how the extra space might be used. Here's a quick concept drawing, with the added parts highlighted.

I don't yet have any comments on the new stuff, but I will note that traditional pin 12 is mislabeled as pin 10.

I assume that at least pins 24-33 will be the same as the underneath pins on the T4 in terms of functionality (i.e. pin 24 has A10, TX6, SCL2 and PWM functionality). If not, it may be useful to renumber the new pins to reduce the amount of #ifdef's needed.

For pins 34-39, aren't these brought out in the SD card also? I don't know whether or not people use a micro SD card more, or want to use those pins for a third SPI port and alternates for RX5/TX5. I could imagine using either the fake micro SD card to bring out those pins if people wanted the 3rd SPI port, or using the through hole pins to connect to a micro SD card reader with 4 bit SDIO.

Generally I tend to think about low power usage in terms of using batteries, while with ethernet devices, that tends to mean either A/C power is available, or using power over ethernet. Of course people may want to use the new board for its other feathers, and not use ethernet.

[defragster]

With a second LDO that was switchable - it could power the ethernet PHY - and maybe the SDIO. The PHY draws power when OFF, but the SDIO takes a lot of power when on - and the second LDO could then power displays of other. When @mjs513 hooked GPS to his T_3.5 (?) it was giving trouble without external power IIRC. Same GPS ran okay as I connected for T_3.6. Then there is the addition of a Radio module for this new IOT stuff - it could use power from that 2nd LDO.

[KurtE]

What this extended size T4 should include or not include is always an interesting question. I know there are many who believe you should include a high density connector to allow them to get to everything... There are those like me, who would probably prefer access to the SPI pins that are part of SDIO more than they need/want SD stuff... BUT, I believe that you are going down the correct path, in making a version that is as reasonably close to functionality of the T3.6...

That is:
a) USBHost: Great to have access to this without bottom pins, also including the power handling.
b) SDCard: yes - I often don't use them... But ...
c) SPI - Hopefully have SPI1 pins that don't require using bottom pins. Can still access SPI2 pins (by using SDCard adapter like I have played with on T3.5/6. Maybe add the pins for the fourth hardware SPI port(SPI2 on pins EMC_00, 02,03, 14)
d) Add the 8th UART back in.
e) Maybe other Wire object. I believe we are not using LPI2C2 which are on pins B4,B5...

f) FlexIO - I need to get back to playing with these and also maybe integrating some of my stuff into core? But as you said it might be good to integrate more of the FLEXIO pins, to have full logical port access. Probably best for the first two FLEXIO objects as if I remember correctly these are the only ones that for example have DMA access or the like.

That is all I can think of for this round

[analog&RFmodels]

if there is room i would vote for single or dual dac similar in performance to tlc/t3.5/t3.6

[defragster]

Memory chip pads on the bottom sound cool.

if there is room i would vote for single or dual dac similar in performance to tlc/t3.5/t3.6

1170 specs include a single hardware DAC

[analog&RFmodels]

Memory chip pads on the bottom sound cool.



1170 specs include a single hardware DAC

i don't think he is speaking of the 1170, but rather a bigger T4 with 1062 mpu

nice to know 1170 has an internal dac

[pocolocos]

BLE & WiFi?

[KurtE]

@Paul - If you are looking to fill in FlexIO pins, my personal preference is to fill in more of FlexIO1 and FlexIO2 over FlexIO3 as FlexIO3 does not have any DMA capabilities.

[defragster]

i don't think he is speaking of the 1170, but rather a bigger T4 with 1062 mpu

nice to know 1170 has an internal dac

Indeed for the 1170 there will be one - for the larger 1062 PCB there will still be none as it is not included on the chip.

[Utak]

KurtE send me a link to this interesting thread.

Ok, what I think about the Teensy 4.0, and my idea for a "Long" Version.

First, make the length optional! How? Break/Cut-able! I need a small Teensy 4.0 like it is, but I need 2-4 DACs and I need 5V tolerant Digital Pins, and the fastest Digital Pin read speed I can get.

So, why not make the long board cut-able? I've think about it with the Teensy 3.5, a cut near behind the Reset Button. Because I don't need the additional Pins, and also not the SD-Card Slot. I need a short board :-)

But... then the DACs Pins must not be placed behind the Reset button :-)

If that were possible, it'd be wonderful.