Developer page for a small yet powerful helper board
This board will fill the gap in the low-end area.
Suggestions for functions:
- prototyping board
- 1x 5V Analog Output
- 1x DB25 Male
- 1x DB25 Female
- SPI is gonna be connected to a DB25 connector
- Decide if we need a 4 layer board
- Decide what should be on (functions) Please rate this from 1 to 5, where 1 is a request and 5 is absolutley needed. So we can drop some stuff if it won't fit
Notable application exception is AudiTrigger? (or tractioncontrol input), as that requires LM1815.
- There is no plan to use LM1815 on this board
- kingbright 3x7 segment SMD LED display (eg. KPBA03-123) will not fit
- Unlocked Miracleboard_r00_je.zip
This [image] shows that
- AVR (or ARM?)
- 7 or 8 NPN driving the LEDs
- 1..2 small AHCT logic chips (needed)?
- supply regulator
- DPAK heater FET
Would fit without a button (and without max232 of course). Maybe with 0603, surely with 0402. Could be used for lotsof other interesting tasks as well.
2xDB25 connectors (one at both ends, preferrably a male and a female) and boardsize that fits into standard DB25 => DB25 adapter housing. Note that there is crimpable DB25 for the wire side (soldering has drawbacks).
Given the size of the board and total of 50 pins (of max 5A current each) the connector won't be the limiting factor.
Size: - different from [this drawing we found]
- internal width = 37 mm (37.1mm - tolerance) not 36.07mm. I suggest max 36.2 mm PCB width
- length (see above drawing for size meaning)
- DIM-F = 51 mm
- DIM-D = 37.3 mm from which 3mm is occupied by the connecor pins at both ends, so basically max 31.3 mm available for routing. I suggest max 37.3 mm long PCB.
- plastic when little heat is dissipated on switches
- metal when more heat is dissipated on switches (metal case size is same ??) we have no metal case samples
Why? Possible applications
Note that the big, relatively expensive and powerful boards like v3 with the aviation-grade connector with housing that seals even though it is reparable is too bulky for
- controlling small home-alarm
- house automation equipments (like fans, garage doors and stuff)
- or even just lights at the back of the car.
- converting between communication options like
- serial => LCD
- and serial => CAN
- could replace AudiTrigger?
- should suit as AfreshTiny/OtherUses (without onboard pads for 5-pin JPT connector)
HW features - in brainstorming phase
- ARM LPC2129 or an AVR ?
- min 4 analog inputs
- no MCP3208 (even just 4 AD channels is enough)
- maybe 1..2 resistor inputs (with my trick for measuring charge time of a cap: note that on ARM many input captures are available)
- 2..4 input captured digital inputs
- some more GPIO digital inputs
- 2..4 DPAK switches (FET / IGBT)
- analog output
- several comm options
- CAN (ARM only)
- serial FBUS
- parallel bus: LBUS (master or slave?) - optional
- parallel bus: drive the standard hd44780 LCD. Important for boards that don't have onboard LCD connector. Preferrably straight connection to LCD pinout (no wire crossing).
- LED display - hardly fit
- pushbuttons - hardly fit
A notebook or PDA (or other boards) can talk to it, but directly only through PS2 an LCD (not internal buttons or LEDs).
Some GPIO pins can be used to reflect internal state (error code, etc...) so state can be checked easily with external LEDs or DVM.
ARM or AVR
The drawback of ARM is the split power supply.
5V output is needed for:
- analog output (eg. 5V fake MAP or MAF signal)
- FETgate driving
- PS2 - not sure (5V supply is needed but clock and data signal should be 3V compatible)
5V output NOT needed for:
- on FBUS
- LCD drive (yes, the LCD's inputs are 3V friendly). What about the LCD => CPU direction ? (only the busy signal, which is optional, so...)
In my opinion a logic chip (extremely low price and acceptable footprint; probably just one) like the 259 is suitable to provide the 5V output (for the RC filter of analog output and FET gates). Add 2 small regulators.
With ARM, CAN is possible, and many more advanced features. Now I vote for ARM, but we can continue the function-mapping (considering other boards and overall coverage): maybe AVR is a better choice. But which AVR? Jorgen says (why not write here???) same as AfreshTiny (Atmega8)
Note that there is a big competitor, VemsFrontier/ArmUfo which will be more useful (but will not fit into the DB25-25 adapter housing). So this board can just as well be AVR ... hard to decide...
- not started yet