---------------------------------------------------------------------------- File: ftp://cherupakha.media.mit.edu/pub/projects/miniboard/docs/mbext21.txt More info: fredm@media.mit.edu Last updated: Fri Dec 1 17:05:08 1995 ---------------------------------------------------------------------------- ANNOUNCING THE MINI BOARD 2.1 EXTENDED !!! Fri Oct 7 08:47:04 1994 The Mini Board 2.1 Extended is the latest version of the Mini Board. It is based on the Mini Board 2.0 Extended, and includes the following new features: * full six-wire SPI jacks include power, ground, and all four SPI wires. * optional diode protection prevents reverse-polarity voltage input when using DC power jack. * power and ground on Port A headers may be bridged to motor power and ground, allowing RC servos to be plugged directly into the Port A header (when using a 5.5 to 6v power supply). SEE NOTE BELOW. * extra space between PLCC socket and female header connectors to allow for newer, slightly larger PLCC sockets. * mounting holes drilled for single RJ11 jack (for RS-232 serial), saving money on triple RJ11 jack if SPI ports are not to be used. Download the file pub/projects/miniboard/docs/mbext21.PS.Z to see the silkscreen of the new board. NOTE REGARDING THE PORT A HEADERS (IMPORTANT!!!) On the MB 2.1ext, the Port A power and ground headers come disconnected. You may jumper them to either CPU power or motor power (the power trace) and CPU ground or motor ground (the ground trace). JUMPER ONLY ON ONE SIDE OF THE OPEN TRACES. On the top side of the board, there is the +5v uproc supply on the left and direct motor voltage supply on the right. On the bottom side, there is uproc ground on the left and motor ground on the right. * If you want to use the Port A for normal digital I/O, jumper only on the left to the microprocessor supplies. * If you want to use Port A for driving servo motors, jumper only on the right to the motor supplies. DO NOT EVER JUMPER ON BOTH SIDES, because this will flood the CPU with the motor voltage, and short the CPU ground to the motor ground. ANNOUNCING THE MINI BOARD 2.0 EXTENDED Fred Martin fredm@media.mit.edu Sun Mar 6 12:09:01 1994 The message is to announce the first revision of the Mini Board 2.0 design since it was released in June 1992. The Mini Board 2.0 Extended is a small revision of the original design. It is 0.45 inches longer than the original. The extra length adds following features: * two real mounting holes so the board can be bolted down to something. * 2.1 mm coaxial DC power jack as an alternate method to apply power to the board. Either the original screw terminal block or the DC power jack may be used. * SPDT slide switch to switch power from DC jack on and off. If power is applied from screw terminal block, slide switch is not part of the power circuit. * the extra .45" of length may be chopped off to save space; the above three features are then lost. In addition to the above features supported on the extra board area, the main board area has been revised to include the following: * TTL-level 6811 TxD and RxD pins exposed to female header jacks. These can be used to communicate with other TTL level async serial devices, or can be temporarily jumpered together and tied via 10K resistor to +5v to allowing booting of 512 byte of EEPROM 'A1 versions of the 6811. * if IRQ button is not installed, a Dallas Semiconductor DS1233 "econo-reset" chip may be mounted instead. This chip assures correct power-on reset operation of 6811 for "mission critical" applications. (Most of the time the 6811 boots properly when power is applied, but the DS1233 may be used to insure that it -always- boots properly.) I hope that these new features will be valuable to the community of Mini Board users. -Fred Additional notes: 1. A PostScript file of the silkscreen of the Mini Board 2.0 Extended may be retrieved from the anonymous FTP server cherupakha.media.mit.edu (IP address 18.85.0.47) in file pub/miniboard/docs/mbextend.PS.Z (a Unix compressed file). The file illustrates all of the new features except the two mounting holes, which are not marked on the silkscreen. The mounting holes are located in the obvious places: above the slide switch and below the DC power jack. 2. The slide switch is part number CKN5001-ND from Digikey. The DC power jack is part number SC1047-ND from Digikey. (Both of these part numbers are present on the silkscreen.) 3. In order to use the Dallas Semiconductor DS1233 chip, an additional 0.1 uF capacitor is required. ---- Fred Martin | fredm@media.mit.edu | (617) 253-5108 | 20 Ames St. Rm. E15-320 Epistemology and Learning Group, MIT Media Lab | Cambridge, MA 02139 USA