Micro-B USB Port
On the bottom edge of the board is the micro-B USB port. This port can be used for sending or receiving data from an attached USB device with the MAX3421E. Since it's an "OTG" connector, you'll need a basic OTG adapter (such as those sold for use with the Pi Zero) to convert to type A.
MAX3421E Control Pins
The MAX3421E USB Host chip on the BFF uses SPI plus an IRQ pin to send data to just about any USB device.
- MOSI - This is the SPI MOSI (Microcontroller Out / Serial In) pin.
- MISO - This is the SPI MISO (Microcontroller In Serial Out) pin.
- SCK - This is the SPI clock input pin.
- CS - This is the chip select pin. It is connected to pin A1 on the BFF. It is also broken out directly next to pin A1.
- IRQ - This is the interrupt pin for the MAX3421E. It is connected to pin A2 on the BFF and is broken out directly next to pin A2.
On the first batch of boards, the IRQ and CS silkscreen labels are swapped. Pin A1 is CS, labeled IRQ; pin A2 is IRQ, labeled CS.
5V Enable Pin and Jumper
- 5VEN - Directly next to pin A0 on the BFF is a pin labeled 5VEN. This is the 5V enable output from the 5V selection circuitry. If you tie this pin to ground, it can disable 5V power to the micro-B USB port, effectively turning off your connected USB device.
- 5V Enable Jumper - A0 - On the back of the BFF, to the left of the 5VEN pin, is an open jumper pad surrounding pin A0. If you solder this jumper closed you will connect the 5V enable pin to A0 on the BFF. This means you can then enable or disable 5V to the micro-B USB port with this GPIO pin.
- 5V Enable Jumper - GPOUT0 - On the back of the BFF, to the right of the 5VEN pin, is an open jumper. It is outlined in white on the board silk. If you solder this jumper closed you will connect the 5V enable pin to GPOUT0 (general purpose output 0) on the MAX3421E. This output is controllable over SPI, which means you can then enable or disable 5V to the micro-B USB port in software. GPOUT0 is only accessible with Arduino.
Page last edited May 03, 2024
Text editor powered by tinymce.