DemUino2

Photos

DISCLAIMER

I can not be held responsible for any damage, either to yourself, others or equipment by anyone reading this document and then trying to replicate my efforts.

ACKNOWLEDGEMENT

Let me state that this project would have taken considerably longer with dubious end results if it were not for the gifted fans out there who selfishlessly supply the freeware libraries for everyone to use. Thank you all :-)

FEATURES

• Based on the ATMEGA644-20PU with 64KB flash, 4KB SRAM and 2KB EEPROM.

• LCD character display 4 lines by 40 columns with linebars

• create up to 8 custom characters for user graphics

• support for interactive and batch modes

• full screen line editor

• if-else conditional, do-while and for-next loops plus goto and gosub statements for branching
  

• compute Convolution and DFT of sequences as well as system Transfer Functions plus any combination of arithmetic and mathematical expressions in RPN

• User defined mathematical functions

• run interactively commands while a program is running

• run mini loops/programs from the command line

• execute periodically commands

• system variables allow for timed events, average, rms, min and max values from analog pins, etc

• 104 bytes of different types of user variables that share memory among them to interact with system variables and commands allowing for bytes, short and long integers as well as floating point numbers

• up to 1000 bytes of dynamic memory to work with ranging from unsigned chars to floating point numbers

• ability to modify program data and code on the fly

• mini oscilloscope application 16x20 dots and 50KB/sec sampling rate

• low frequency logic capture - 3200 samples in 10.8 msec

• slow and fast GPIO ( ~1KB/sec and >500KB/sec)

• save/load programs and data to/from SD card, EEPROM and PC

• autoexec to load and run a program from EEPROM after each reset

• up to 23 GPIO pins (SPI included but no SD, no RS232)

• BUZZER for sound effects

HARDWARE

The schematic for the development board is shown below. The available pins left on the MCU were connected to female pinheaders so as to facilitate the wiring to breadboard and further experimentation. The hardware serial library has a problem with SIGNAL and the read function is problematic. I used IDE 1.0.4 since 00xx versions were incompatible with several library calls and had a flood of compiler errors. Replacing SIGNAL with ISR calls did not help as there were again library incompatibilities with some classes. Instead, the altsoftserial library (D13,D14) is used for the occasional interaction with a PC via RS232. The hardware UART pair is used by the bootloader to burn firmware. Both pairs of pins are available for GPIO when not used for serial IO. The SEIKO display is an ancient 90s model that was lying unused in my neglected and wretched lab. Modifying the code to run on smaller displays involves, mostly, altering the lcdupdate() internal function.

The appendix shows the circuit used to interface to an SD card. Thanks to www.roland-riegel.de and his useful library I extracted and modified the raw part of it to allocate dynamically the data buffer and thus save RAM and also to include support for the atmega644.

COMMANDS

All arguments/operators must be separated by at least a single space character and their order is important. Program statements start with a 2-digit number 00,...,99 followed by at least a space. These 3 first characters are mandatory and their position is fixed. Following that can be any valid statement or expression for execution. However, any text can be inserted provided there is no execution of the program. All commands and arguments are parsed by strtok as strings which means that most arguments can be variables instead of constants - where appropriate - and spaces are not critical. There is limited support for strings (double quotes) and string words (single quotes). So printing a message like 'pr “Hello World' will produce the appropriate output only if modified in a single word, such as, 'pr “HelloWorld'. There is an minor bug that renders the cursor invisible whenever output is on the 3rd and 4th lines. Simply press ESC to make it reappear (also ‘cl’).

Multiple statements can be entered on the same line and separated by a semicolon (;) - no white space needed. The following commands can not be part of a multiple statement construct: {if,else,fr,nx,do,wh,en}.

There is an autoexec-like-feature that allows the user to load a program and run it automatically after each reset. Depending on the value at EEPROM address 0 the unit will either load and run program ‘start’ (EEPROM(0)==1) or simply wait for keyboard input.

Summary of Commands & Expressions

“ : a nonprintable comment line

{} : expression evaluated

00-99 : a two digit number by itself is equivalent to goto

ai : attach interrupt 0,1,2

anfo: display the average, r.m.s, max. and min. of axxx

apl : plot the contents of axx using bar graph

ar : analog read

aw : ‘analog write’ per sanguino or more properly pwm

ca : analog capture in an array

cc : create custom characters

cl : clears the display

cmd: execute the contents of pointer p or a

cmno: find a line number index in *Prgm[]

conv : convolution of two arrays

DFT : discrete fourier transform

di : wait for a series of pulses and measure duration and timing

dim: allocate memory for user array axxx

dl : delay

do : in conjunction with ‘wh’

dr : digital read any pin

dw : digital write any pin

ed : editor mode for batch commands / load program from PC

el : EEPROM read access function

else : in conjunction with ‘if’

end : the END statement of a program

ensb: ends subroutine

es : EEPROM write access function

ev : EEPROM viewer

Fn : user function definition and evaluation

fl : simple moving average filter

fr : for-next loop (fr-nx)

go : jump to program step

gosb: continue execution to subroutine

gt : waits for user input

if : test condition

io : slow GPIO 1-15 bits

jmp: similar to goto

la : logic capture in an array

ld : load/merge program from EEPROM

loop: execute multiple commands repeatedly in interactive mode

lpar : define loop command parameters

ls : list mode / send program to PC a line at a time

ml : get time

mm : display free memory

nos : converts number to string

nx : in conjunction with ‘fr’

on:<Var> : execute a subroutine periodically

pa : fast 8-bit output from port A

pl : plot array cxx

pm : set pins for in or output

pol : specify the polynomials for the transfer function

ppar: set apl plotting parameters

pr : prints a message or value

pw : pwm with keyboard control

rn : run the program in RAM

rng : range command for array operations

rs : soft reset

rx : receive a character via RS232

sc : enable/disable serial communication

sd : SD card access functions

si : synchronous serial input with clock and data pins

sm : mini oscilloscope app

snd : fast user modulated pwm at 7.8KHz

sno : string to number

so : synchronous serial output with clock and data pins

strc : copy string to array

strf : find string in array/ return string length

sub : declares subroutine

sv : save program to EEPROM

tf : transfer function computation, plotting and printing

tn : beep a tone

tx : transmit a number via RS232

xy : write a user defined character on LCD

wh: a do-while loop used in conjunction with ‘do’

Simple Constructs for Expressions in RPN Notation

Var1 = Var2 Var3 + : add

Var1 = Var2 Var3 - : subtract

Var1 = Var2 Var3 * : multiply

Var1 = Var2 Var3 / : divide

Var1 = Var2 Var3 % : modulo - integers only

Var1 = Var2 INV : reciprocal

Var1 = Var2 Var3 > : greater than

Var1 = Var2 Var3 < : less than

Var1 = Var2 Var3 = : equality

Var1 = Var2 Var3 != : inequality

Var1 = Var2 Var3 && : logical AND

Var1 = Var2 Var3 || : logical OR

Var1 = Var2 ! : boolean not

Var1 = Var2 SIN : sinusoid

Var1 = Var2 ASN : arcsin

Var1 = Var2 TAN : tangent

Var1 = Var2 ATN : arctangent

Var1 = Var2 LOG : log10

Var1 = Var2 EXP : exponential

Var1 = Var2 Var3 POW : power

Var1 = Var2 SQR : square root

Var1 = Var2 SQ : squared

Var1 = Var2 : equate

Var1 = Var1 Var2 Var3 BW

Var1 = Var2 Var3 BR

Var1 = Var2 Var3 & : bitwise AND

Var1 = Var2 Var3 | : bitwise OR

Var1 = Var2 Var3 << : bit left-shift – shift Var2 by Var3 bits to the left

Var1 = Var2 Var3 >> : bit right-shift – shift Var2 by Var3 bits to the right

#p : undefinedundefinedundefinedundefinedundefined

project home page 

https://www.sites.google.com/site/demeterart/home/demuino2