Teensy Breadboard

Teensy Breadboard

Combines a $16 ATmega32U4 based carrier from http://www.pjrc.com/teensy with Pololus on a solderless breadboard. Runs Teacup through integrated USB using LUFA serial at 38400 baud. (Teensy is capable of 12MBit/sec communication per [[1]]. Tested at 230400 baud with CoolTerm, and 250000 Baud with Pronterface with modified Teacup using Teensy's usb_serial* routines.) Possible upgrade path to the AT90USB1286 on a $24 Teensy++ towards Teensylu and Printrboard compatibility. Possible upgrade path to a 32 bit ARM Cortex-M4 48MHz processor on Teensy 3.0 (Was $22 on Kickstarter 2012-09-15).

Firmware

• Teacup/Gen7 branch: https://github.com/triffid/Teacup_Firmware/tree/Gen7 my modifications are in https://github.com/drf5n/Teacup_Firmware/tree/Gen7 Most of the modifications are in triffid's upstream Gen7 branch.

Pinout

My pinouts from https://github.com/triffid/Teacup_Firmware/blob/Gen7/config.teensy.h :

/* Machine Pin Definitions - make sure to avoid duplicate usage of a pin - comment out pins not in use, as this drops the corresponding code and makes operations faster Teensy http://www.pjrc.com/teensy ATMega64U4 carrier: DaveX plan for Wallace: USB GND GND |-----#####-----| +5V ATX +5SB ATX PS_ON 0 |b0 ##### F0| 21 A0 Extruder TC X_MIN 1 |b1 f1| 20 A1 Bed TC Y_MIN 2 |b2 /=e6 f4| 19 A2 Stepper -ENABLE (or -SLEEP) Z_MIN 3 |b3 * * f5| 18 A3 STEP X PWM 4 |b7 aref=/ f6| 17 A4 DIR X PWM 5 |d0 f7| 16 A5 STEP Y 6 |d1 b6| 15 A6 PWM DIR Y 7 |d2 V G R b5| 14 A7 STEP Z Fan 8 |d3 d c n S d b4| 13 A8 DIR Z Bed Heat PWM 9 |d6 5 c d T 4 d7| 12 A9 PWM STEP E Extruder Heat PWM 10 |d7 * * * * * d6| 11 A10 (led) DIR E -------------------- 23 ^ \ \----22 A11 \------ RST Interior E6: 24, AIN0, INT6 Interior Aref : Aref End d5 : 23 End d4 : 22, A1

With This configuration there remain 4 (or 7, if you count the three in the interior) IO pins leftover.

Options

• The version shown above shows a Teensy 2.0, a couple Pololus with voltage regulators, a couple regular Pololus, a single heater output for the extruder, no endstops, and a single thermistor circuit. The Pololus are fed 12v through separate lines.
• The $24 Teensy 2.0++ uses an AT90USB1286, which matches the Teensylu and Printrboard chips, which may make compiling and configuring a firmware easier. It also has lots of extra IO pins.
• The Teensy 2.0 has 25 IO pins, 12 of them can do analog input, while 7 of them do PWM output, which is more than enough for the 15 pins required for 4 steppers, 2 heaters, 2 thermistors, and 3 endstops.

Discussion on first build

• 2012-09-29The original thermistor circuit is pretty noisy, with successive dT up to ~10C. The thermistor is fed off of the +5 rail supplied by an ATX power supply, and uses a 4.7uf capacitor, small relative to other electronics. Using a regulated 5V supply and a 10uf capacitor as in Ramps#Schematic or Sanguinololu should help with the noise.