Designing with MicroMod
Contributors:
Nate
Nate 
Pin Specifications
The MicroMod interface is defined as follows:
Useful component datasheets:
Here is the pinout description information in table form:
| Signal Group | Signal | I/O | Description | Voltage |
|---|---|---|---|---|
| Power | 3.3V | I | 3.3V Source | 3.3V |
| GND | Return current path | 0V | ||
| USB_VIN | I | USB VIN compliant to the USB 2.0 Specification. Connect to any pins on the processor that require 5V for USB functionality. | 4.8-5.2V | |
| RTC_3V_BATT | I | 3V provided by external coin cell or mini battery. Max draw = 100uA. Connect to pins that maintain an RTC during power loss. Can be left NC. | 3V | |
| 3.3V_EN | O | Controls the carrier board's main voltage regulator. Voltages above 1V will enable 3.3V power path. Can be left NC. If implemented, carrier board must supply pullup resistor and 3.3V clamping on regulator enable pin. | 3.3V | |
| BATT_VIN/3 | I | Carrier board raw voltage over 3. 1/3 resistor divider is implemented on carrier board. Amplify the analog signal as needed to enable full 0-3.3V range. | 3.3V | |
| Reset | Reset | I | Input to processor. Open drain with pull up on processor board. Pulling low resets processor. | 3.3V |
| Boot | I | Input to processor. Open drain with pull up on processor board. Pulling low puts processor into special boot mode. Can be left NC. | ||
| USB | USB_D+ USB_D- |
I/0 | USB Data ± Differential serial data interface compliant to the USB 2.0 specification. If a UART is required for programming, USB+/- must be routed to a USB-to-serial conversion IC on the processor board. | |
| USB_HOST | USBHOST_D+ USBHOST_D- |
I/0 | For processors that support USB Host Mode. USB Data ± differential serial data interface compliant to the USB 2.0 specification. Can be left NC. | |
| CAN | CAN_RX | I | CAN Bus Receive Data | 3.3V |
| CAN_TX | O | CAN Bus Transmit Data | 3.3V | |
| UART | UART_RX1 | I | UART Receive Data | 3.3V |
| UART_TX1 | O | UART Transmit Data | 3.3V | |
| UART RTS1 | O | UART Ready to Send | 3.3V | |
| UART CTS1 | I | UART Clear to Send | 3.3V | |
| UART_RX2 | I | 2nd UART Receive Data | 3.3V | |
| UART_TX2 | O | 2nd UART Transmit Data | 3.3V | |
| Note: UART1/2 must be unencumbered (not attached to a USB-to-serial conversion IC). | ||||
| Note: UART0 is not shown. Primary debug serial is done over USB. Serial.print() should print over USB, not TX1. | ||||
| I2C | I2C_SCL | I/O | I2C Clock. Open drain with pull up on carrier board. | 3.3V |
| I2C_SDA | I/O | I2C Data. Open drain with pull up on carrier board. | 3.3V | |
| I2C_INT# | I | Interrupt notification from carrier board to processor. Open drain with pull up on carrier board. Active Low. | 3.3V | |
| I2C_SCL1 | I/O | 2nd I2C Clock. Open drain with pull up on carrier board. | 3.3V | |
| I2C_SDA1 | I/O | 2nd I2C Data. Open drain with pull up on carrier board. | 3.3V | |
| SPI/SDIO | SPI_SCK SDIO_CLK |
O | SPI Clock. Secondary use: SDIO Clock. | 3.3V |
| SPI_COPI SDIO_CMD |
IO | SPI Controller Out Peripheral In. Secondary use: SDIO Command Interface. | 3.3V | |
| SPI_CIPO SDIO_DATA0 |
I/O | SPI Controller In Peripheral Out. Secondary use: SDIO data exchange bit 0. | 3.3V | |
| SDIO_DATA1 | I/O | SDIO data exchange bit 1 | 3.3V | |
| SDIO_DATA2 | I/O | SDIO data exchange bit 2 | 3.3V | |
| SPI_CS SDIO_DATA3 |
I/O | SPI Chip select. Active low. Secondary use: SDIO data exchange bit 3. | 3.3V | |
| Note: The carrier board SD socket can fall back to SPI if lines are routed correctly. Connect multiple pins to obtain dual function as necessary. For example, if CIPO1 is a different pin from DATA0 on processor, then route both CIPO1 and DATA0 to SDIO_DATA0 on board edge. | ||||
| SPI_CIPO1 | I | 2nd SPI Controller In, Peripheral Out | 3.3V | |
| SPI_COPI1 | O | 2nd Controller Out, Peripheral In | 3.3V | |
| SPI_SCK1 | O | 2nd SPI clock | 3.3V | |
| SPI_CS#1 | O | 2nd SPI chip select. Active low. Can be routed to GPIO if hardware CS is not used. | 3.3V | |
| AUDIO | AUD_MCLK | O | Audio Master Clock | 3.3V |
| AUD_OUT PCM_OUT I2S_OUT CAM_MCLK |
O | Audio data output. PCM synchronous data output. I2S serial data out. Camera master clock. | 3.3V | |
| AUD_IN PCM_IN I2S_IN CAM_PCLK |
I | Audio data input. PCM synchronous data inut/I2S serial data in. Camera peripheral clock. | 3.3V | |
| AUD_LRCLK PCM_SYNC I2S_WS PDM_DATA |
I/O | Audio left/right clock. PCM synchronous data SYNC. I2S word select. PDM data. | 3.3V | |
| AUD_BLCK PCM_CLK I2S_SCK PDM_CLK |
O | Audio bit clock. PCM clock. I2S continuous serial clock. PDM clock. | 3.3V | |
| SWD | SWDIO | I/O | Serial Wire Debug I/O. Connect if processor supports SWD. Can be left NC. | 3.3V |
| SWDCK | I | Serial wire debug clock. Connect if processor supports SWD. Can be left NC. | 3.3V | |
| ADC | A0 | I | Analog to digital converter 0. Amplify the analog signal as needed to enable full 0-3.3V range. | 3.3V |
| A1 | I | Analog to digital converter 1. Amplify the analog signal as needed to enable full 0-3.3V range. | 3.3V | |
| PWM | PWM0 | O | Pulse width modulated output 0. | 3.3V |
| PWM1 | O | Pulse width modulated output 1. | 3.3V | |
| Digital | D0 | I/O | General digital input/output pin. | 3.3V |
| D1 CAM_TRIG |
I/O | General digital input/output pin. Camera trigger. | 3.3V | |
| GPIO/BUS | G0/BUS0 | I/O | General purpose pins. Any unused processor pins should be assigned to Gx with ADC + PWM capable pins given priority (0, 1, 2, etc) positions. The intent is to guarantee PWM, ADC, and digital pin functionality on ADC/PWM/Digital specific pins. Whereas Gx pins do not guarantee ADC/PWM function. Alternatively, pins can be used to support a fast read/write 8-bit wide or 4-bit wide bus. | 3.3V |
| G1/BUS1 | I/O | 33V | ||
| G2/BUS2 | I/O | 3.3V | ||
| G3/BUS3 | I/O | 3.3V | ||
| G4/BUS4 | I/O | 3.3V | ||
| G5/BUS5 | I/O | 3.3V | ||
| G6/BUS6 | I/O | 3.3V | ||
| G7/BUS7 | I/O | 3.3V | ||
| G8 | I/O | General purpose pin. | 3.3V | |
| G9 ADC_D- CAM_HSYNC |
I/O | Differential ADC input if available. Camera horizontal sync. | 3.3V | |
| G10 ADC_D+ CAM_VSYNC |
I/O | Differential ADC input if available. Camera vertical sync. | 3.3V | |
| G11 SWO |
I/O | General purpose pin. Serial Wire Output. | 3.3V | |