VEX Cortex Microcontroller

From VEX Wiki

Product Information

The VEX Cortex Microcontroller is the latest VEX Microcontroller. A microcontroller coordinates the flow of information and power on the robot. All other electronic system components must interface to the Microcontroller.

Links

VEX Cortex Microcontroller Product Page
VEX Cortex Microcontroller/VEXnet Joystick User Guide (1MB, PDF, 08-18-2011)
VEX Cortex Microcontroller Pinout Guide (197kb, PDF, 12-06-2010)
Refer to the VEXnet Firmware Upgrade Utility
Bootloader & Firmware Change Log for the VEX Cortex Microcontroller & VEXnet Joystick
VEXnet MAC Utility easyC V4 for Cortex Product Page ROBOTC for Cortex & PIC Product Page

VEXnet Wireless

The VEX Cortex Microcontroller uses 802.11b/g for communications through a proprietary VEXnet implementation. This implementation is designed to eliminate the need for any knowledge of IP addresses, MAC addresses, security settings, and IP protocols. Just turn it on and it automatically connects to the correct Joystick. Future VEXnet enhancements include plugging the VEXnet USB Adapter into your PC for programming, debugging, and driving from the PC.

Note: See the VEX Arm9 Microcontroller for open communication to 802.11 networks, PC's, and across the internet.

Features

• VEXnet bi-directional wireless communication (based on 802.11g)
  • Wireless driving, wireless debugging, and wireless downloading
• Also support for two 75MHz crystal transmitters and receivers
• STMicroelectronics ARM Cortex-M3 user processor
  • 90 MIPS performance (9x the V0.5 microcontroller)
  • 384KB Flash (12x the V0.5 microcontroller)
  • 64KB RAM (35x the V0.5 microcontroller)
• easyC for Cortex and ROBOTC programmable
• One I2C port (will connect to multiple new smart sensors)
• Two fast UART serial ports
• 8 high resolution analog inputs (12bit)
• 12 fast digital I/O (all can be interrupts)
• 10 motor ports
  • 8 standard 3-wire PWM
  • 2 new 2-wire motor ports
• Total motor current limit is 2x original controller
  • Motor ports 1-5 share a 4 Amp PTC (Over-current protection device)
  • Motor ports 6-10 share a second 4 Amp PTC (Over-current protection device)
• DAC speaker output (sound, voice, music output to external speaker)
• Latches on all 2-wire and 3-wire IO sockets
• Same size as VEX Microcontroller V0.5

IO Ports

• Input Impedance: Analog - The 8 analog inputs each consist of a 470K pull-up to +5V, a series resistance of 10K and a 20K pull-down resistance to the uP.
• Analog characteristics:
  • 3 dB bandwidth of 16 kHz.
  • Analog input range: 0.0 v to 5.0 v.
  • Tolerant of -0.5v to +5.5v.
  • Only configurable as analog inputs.
• Input Impedance: Digital - The 12 digital inputs each consist of a 1K series resistance and a weak processor pull-up to +3.3V. Each Digital Input can also be configured as a Digital Output.
• Interrupts: All digital inputs can be configured as interrupts except for Digital 10.
• Digital characteristics:
  • 3 dB bandwidth of 150 kHz.
  • Needs 0.0 to 0.6 volts for a low and 2.5 to 5.0 volts for a high.
  • Tolerant of -0.5v to +5.5v.
  • Can drive a 1 mA load to 1.6v or lower for a low and 1.4 volts or higher for a high.
  • All digital lines can be configured as inputs or outputs.
• SP characteristic:
  • SP Output: A Digital-to-Analog (DAC) output when configured by compiler.
  • Drive primarily limited by 5K processor resistance.
  • Output swing into open load is 0.2v to 3.1v, typical.
• PWM Outputs:
  • These 8 ports can drive an open circuit to 0.6v or lower for a low and 2.4 volts or higher for a high.
  • They can drive a 1 mA load to 1.0v or lower for a low and 2.4 volts or higher for a high.
• Pinout: (see also: Cortex Pin-out)
  • Digital, Analog, PWM Outputs: Outside pin (closest to the controller edge) Ground
  • Digital, Analog Outputs: Center pin (or middle pin) + 5 Volts, 1 Amp Max combined total from all pins
  • PWM Outputs: Center pin (or middle pin) + Battery Power, 4 Amps Max combined total from all pins for Motors 2 - 5 and 4 amps combined for Motors 6 - 9
  • Digital, Analog, PWM Outputs: Inside pin (furt.hest from the controller edge) Signal / Control line
  • 2-Wire Motor Outputs:
    • Two pins each for Motor 1 and for Motor 10.
    • Motor 1 shares 4 amp max with Motors 2 - 5.
    • Motor 10 shares 4 amp max with Motors 6 - 9.

UART Ports

• 0 to 3.3v logic I/O, 5V tolerant
• Data rate, word width, etc set by compiler
• Factory default: 19.2 kbaud, 8 data bits, no parity, talks with VEX LCD.
• See Cortex Pin-out for wiring details

I2C Ports

• 0 to 3.3v logic I/O
• Data rate, word width, etc set by compiler
• See Cortex Pin-out for wiring details

RX1 and RX2 Ports

• Connects to 75 MHz receivers
• Pin 1 - Power +5 volts (the right most pin when looking at the front connector on the VEX Controller)
• Pin 2 - Receiver
• Pin 3 - Gnd
• Pin 4 - Tether Detect (the left most pin when looking at the front connector on the VEX Controller))

LED Indications

Please refer to VEX Cortex Microcontroller/VEXnet Joystick User Guide