Project Recap: Binary Clock

Binary Clock Layout
Originally uploaded by hithisishal

This was one of the first microcontroller projects that I completed. I was working on a nixie clock at the time, and while writing the binary to decimal converter, I decided to pull over and make a pure binary clock.

The first version was drawn with a sharpie onto copper by hand. It is ugly (and in my photostream if you want to see). A few months later, I was assigned a project in school that involved getting a board fabbed. I had plenty of room left before reaching the minimum size, so I made a few of these binary clocks. This was my second time doing a layout in Eagle (the first being the school project), and I didn't really know what I was doing. I made a layout, without making a schematic first. Luckily, the layout worked, but I still don't have a schematic drawn up for this project - I will if there is enough demand. There are 2 things about the layout that I would change if i made more - the switch holes are a bit off, and I would add an ICSP header. I finished up 4 of these clocks, and gave two as gifts. The others are currently at my parents' house, though. I will be home and have some pictures in a few months.

Anyway, I think the value of this project is in the code. I learned PIC assembly from John Morton's PIC: Your Personal Introductory Course. I have since moved on to C, but I sometimes miss coding in assembly. The code that follows is very likely not efficient and may have remnants of past versions, but it should be easy to follow, and got the job done.

;********************************************************
;* Binary Clock                                               *
;* Written By: Hal Emmer                                      *
;* Date: July, 2006                                           *
;* version: 2.0 modified to use interrupts                    *
;* for PIc: 16f628a                                           *
;* clock: internal oscillator                                 *
;**************************************************************


    LIST            P=16F628a
    ERRORLEVEL      -302    ; suppress bank selection messages
    __CONFIG        3F18H   ; int oscillator


PCL     EQU     2               ; bits and registers are defined here to 
STATUS  EQU     3               ; make this program self contained.
PORTA   EQU     5
PORTB   EQU     6
INTCON  EQU     0BH
TRISA   EQU     85H
TRISB   EQU     86H
OPTREG  EQU     81H
CMCON   EQU     1FH
TMR0    EQU     01H

W       EQU     0
F       EQU     1
C       EQU     0               ; bits in STATUS
Z       EQU     2
RP0     EQU     5

T0IF    EQU     2               ; bit in INTCON



    CBLOCK  20H             ; define variables required

    TICKS
    SEGS                    ; one bit per segment: "-gfedcba"
    SEC
    MIN
    HOUR
    FRAME                   ; used to decide when to display time
    HHMM                    ; one bit per digit displayed
    COUNT                   ; scratch register
    DIGIT                   ; last digit displayed
    DELVAR            ; delay counter
    SPEED
    SPEED2            ; used to set time
    LIGHT            ; hardware compensation
    COUNT1
    W_SAVE
    STATUS_SAVE
    ENDC


    ;*********************************;
    ;         Initialization          ;
    ;*********************************;

    ORG     0
    goto    INIT
    ORG        4
    goto    ISR    

INIT    CLRF    SEC
    CLRF     MIN
    CLRF     HOUR
    CLRF     FRAME
    CLRF     PORTA
    CLRF     PORTB
    CLRF     CMCON
    MOVLW    07H
    MOVWF    CMCON
    movlw    h'C4'
    movwf    SPEED
    movlw    d'59'
    movwf    SPEED2
    BSF      STATUS,RP0      ; select register bank 1
    CLRF     TRISB
    BSF      TRISB,6        ; RB6 is an input min button
    BSF      TRISB,7        ; RB7 is an input hr button
    CLRF     TRISA        
    bsf      TRISA,4        ; RA4 is clockin           
    MOVLW    b'00101000'    ; t0cs is RA4/T0CKI
    MOVWF    OPTREG          ; prescalar assigned to WDT (no prescaler)
    BCF      STATUS,RP0      ; reselect bank 0
    BSF      INTCON, 5    ; t0 overflow interrupt enable
    BSF      INTCON, 7       ; global interrupt enable

    ;*********************************;
    ;          Main Program           ;
    ;*********************************;

MAIN    
    CALL    DISPLAY         ; continue to display
    GOTO    MAIN            ; unless interrupted

    ;*********************************;
    ;  Real-time clock algorithm      ;
    ;*********************************;

CLOCK   
    INCF    SEC,F           ; second for next second
    MOVF    SEC,W
    SUBWF   SPEED2,W
    BTFSC   STATUS,C
     RETURN

    CLRF    SEC
    INCF    MIN,F
    MOVF    MIN,W
    SUBLW   d'59'
    BTFSC   STATUS,C
     RETURN

    CLRF    MIN
    INCF    HOUR,F
    MOVF    HOUR,W
    SUBLW   d'23'
    BTFSS   STATUS,C 
    CLRF    HOUR
    RETURN
    
    ;*********************************;
    ;       Displays digit in W       ;
    ;*********************************;

DISPLAY    clrf    LIGHT
    btfsc  SEC,0        ; these lines are used to translate
    bsf    LIGHT,3        ; the stored values to the physical pins
    btfsc  SEC,1        ; that the LEdS are connected to.  Ideally,
    bsf    LIGHT,2        ; they would not be required, but I wired some
    btfsc  SEC,2        ; stuff backwards, so I had to fix it in 
    bsf    LIGHT,1        ; firmware - no biggie.
    btfsc  SEC,3
    bsf    LIGHT,0    
    btfsc  SEC,4
    bsf    LIGHT,4
    btfsc  SEC,5
    bsf    LIGHT,5
    movfw  LIGHT
    MOVWF  PORTB           ; and display
    BSF    PORTA,1
    CALL   DELAY2        ; short delay
    BCF    PORTA,1          
    
    clrf   LIGHT
    btfsc  MIN,0
    bsf    LIGHT,3
    btfsc  MIN,1
    bsf    LIGHT,2
    btfsc  MIN,2
    bsf    LIGHT,1
    btfsc  MIN,3
    bsf    LIGHT,0    
    btfsc  MIN,4
    bsf    LIGHT,4
    btfsc  MIN,5
    bsf    LIGHT,5
    movfw  LIGHT        
    MOVWF  PORTB           ; and display
    BSF    PORTA,0
    CALL   DELAY2        ; short delay
    BCF    PORTA,0
    
    clrf   LIGHT
    btfsc  HOUR,0
    bsf    LIGHT,3
    btfsc  HOUR,1
    bsf    LIGHT,2
    btfsc  HOUR,2
    bsf    LIGHT,1
    btfsc  HOUR,3
    bsf    LIGHT,0    
    btfsc  HOUR,4
    bsf    LIGHT,4
    btfsc  HOUR,5
    bsf    LIGHT,5
    movfw  LIGHT          
    MOVWF  PORTB           ; and display
    BSF    PORTA,2
    CALL   DELAY2        ; short delay
    BCF    PORTA,2
    RETURN


    ;*********************************;
    ; Checks for a switch press and   ;
    ; updates digit if displayed      ;
    ;*********************************;
CHKSW   BTFSC   PORTB,6         ; switch closed?
    goto    CLRCNT1         ; no - return 0
    movlw   h'FF'
    movwf   SPEED
    movlw   d'19'
    movwf   SPEED2
    incf    COUNT1,f
    movfw   COUNT1
    SUBLW   5
    BTFSC   STATUS,C
    RETURN
    movlw    h'FF'
    movwf    SPEED
    RETURN

CHKSW2  BTFSC   PORTB,7        ; switch closed?
    RETURN                 ; no
    INCF    HOUR,F         
    MOVF    HOUR,W
    SUBLW   23
    BTFSS   STATUS,C
    CLRF    HOUR
    RETURN

    ;*********************************;
    ; Delay used by switch routine    ;
    ;*********************************;

DELAY   MOVLW   D'12'           ; roughly 100ms delay
        MOVWF   TICKS
DEL1    CALL    DELAY2
        DECFSZ  TICKS,F
        GOTO    DEL1
        RETURN

DELAY2  MOVLW    d'255'        ; 255 cycles or so...will test timing.
    MOVWF    DELVAR
    NOP
    NOP    
    NOP
    NOP
    NOP
    NOP    
    NOP
    NOP
    DECFSZ  DELVAR,F
    GOTO    DELAY2+2
    RETURN

    ;*********************************;
    ; Reset speed timers              ;
    ;*********************************;

CLRCNT1 movlw    h'C4'
    movwf    SPEED
    movlw    d'59'
    movwf    SPEED2
    clrf     COUNT1
    return
    
ISR    MOVWF  W_SAVE            ; save W
    SWAPF     STATUS, W         ; save STATUS 
    MOVWF     STATUS_SAVE
    BCF       STATUS, RP0       ; be sure we are in bank 0    
    BCF       INTCON,2        
    movfw     SPEED
    movwf     TMR0
    movfw     SPEED
    movwf     TMR0
    CALL      CLOCK        ; increment the timer 
    CALL      CHKSW        ; and check the buttons
    CALL      CHKSW2
    SWAPF     STATUS_SAVE, W
    MOVWF     STATUS        ; restore W and STATUS
    SWAPF     W_SAVE, F
    SWAPF     W_SAVE, W    
    RETFIE                ; return from isr
END

Also, a big thanks to Greg Houston for http://formatmysourcecode.blogspot.com/.

Really good iced tea

I surprised myself with this one. It was really easy, and actually came out really good! Without further blabbing,

Ingredients
4 bags Wissotzky Raspberry Black Tea.
10 leaves fresh mint (I might use more next time, but I didn't want to cut too much)
1 lemon
1/2 cup sugar
around 3/4 of a pitcher full of water

In a pot, heat the water. Throw in the tea bags (without paper) when the water looks pretty hot. Let it boil, then turn off the heat. When it cools a bit, add the mint. Juice half the lemon, and cut the other half into quartered slices, and place inside. Add sugar. Let it cool some more. Pour into pitcher, and fill the rest of the way with water, and let cool in fridge. Drink and enjoy.

A better 'Arduino' Stamp (very beta)

avr stamp board layout
Originally uploaded by hithisishal

Edit (7/10/09): I finally got the boards back. I am working out some small problems, and will update soon.

I'm not exactly sure if this is ready to publish, but I don't think I'm going to get any farther until I get a prototype put together, which may be a while down the road. Anyway, my school has a lot of Boe-Bots. The Boe-bot is a really great beginner robotics/microcontroller platform, but that is exactly what it is. They are used for high school students and freshmen in an "Intro to all types of engineering" class. It would be nice to get some more use out of them in higher level classes, and the ability to program them in C would do just that. So I was given the task of designing a board that I could swap with the BASIC Stamp to allow this. The Arduino Mini is almost that, but not quite. There are a number of problems that make it unsuitable to simply stick in a Board of Education (BoE). I aimed to fix all of these:

1. The BS2 has inverters on TX/RX on the board. This way, it can talk RS-232 without a MAX232. The BoE has an FTDI USB to Serial converter, and inverters built in on the board, so it can talk to the BS2 (it ends up inverting the signal twice). The only way to make a board that is hot swappable would be to put inverters on the AVR Stamp as well (or to use a different USB/serial device, but I chose the first option).
2. The BoE has a silk layer saying the pinouts - and these are broken from the socket to headers around a small breadboard. They were shifted by 2 on the Arduino mini. They're still wrong, but closer. Now it's right from 0-8.
3. The BS2 lacks hardware PWM, so pins 12, 13, 14, and 15 are arbitrarily broken out to headers that can connect to the motors. I needed to connect at least 2 of these to Arduino PWM pins, so I chose Arduino pins 9 and 10 (OC1A and OC1B).
4. The Arduino Mini didn't fit in the socket well. I hope I can find headers/pins that will fit better.
5. The Arduino Mini had to be reset before programming. The Mini Pro (and my AVR Stamp) has a switch to make this easier. I hope the DTR will work now, though. I'll see, and perhaps be able to use this board space for an ISP header or breakout for more analog pins in a later revision.

This board layout is totally unconfirmed. Don't make it if you want it to work. Don't complain to me if you make it and it doesn't work.

Eagle files follow. The library contains 2 parts, and the board also uses the Sparkfun library.

Bill of Materials with Digi-Key part numbers
Eagle Board File
Eagle Schematic File
Eagle Library with the two transistors.

Note: I know that I used the words Arduino and AVR interchangeably here. But that's because they mostly are. This project is not official Arduino hardware, and should not be called an Arduino. However, it is very closely based on the Arduino Mini Pro, which basically makes it an Arduino?

Classes are done!

Summer time = hacking time, which should lead to posting time? And it will. But for now I just bought a Game Boy Advance and Flash Cart. I have this GPS data viewer wired up with my Trimble Ace II. I'm reading through TONC, an awesome tutorial. I want to do tons of stuff with it, starting with rewriting that GPS program without the HAM and HEL libraries (mostly as an exercise), and add a waypoint finder so that it could be used for Geocaching.

It's so weird having a 32 bit native datatype.

Single cell white LED flashlight

flashlight_schem
Originally uploaded by hithisishal

I have been quite busy with classes and trying to figure out what to do next year, so I still haven't had a chance to finish up the weather station. Anyway, Here's a little project that I am working on (well, waiting for switches to arrive from DX) for a class under Professor Mark Yim . As I have mentioned before, I am very inexperienced (and frankly, just bad) at mechanical design, but for this project we used a 3D Printer to make the case. The assignment was to make an LED flashlight, just as an intro to the course - expect cooler stuff in the future. I chose to make a small light that will run for a long time (~15 hours off AAA, 35 with a AA).

The circuit is basically straight out of an app note, but I don't think the IC is well embraced by the hobbyist community - I didn't see any designs out there at all, so I figured I would share. Anyway, it's very small, and I was able to keep the entire circuit small with some careful soldering. I also had tons of fun using the 3D printer. The knurling and threads came out so much better than I expected! Although i barely have time to hack, it's really nice to be at a university with all of these resources.

Click on the image to see the rest of the pictures from this project on flickr.

Weather Station Update

Weather Projector Wheel
Originally uploaded by hithisishal

Sorry it's been so long since I last updated. I finished the software, and the mechanics are (as always) holding me up. This time, with the help of Cameron, I laser cut a projection wheel for the project. Light will shine through this wheel, projecting the shape onto a screen, with the color dictated by the forecast temperature, as described in the last post. The shape projected corresponds to the first icon in the forecast section, from Weather Underground, retrieved through the API. The question mark is used for any "chance of" forecast. More on this, and code, soon.

We also took the opportunity to cut 120 snowflakes out of the other side of the box. It's awesome to have all the resources of a university to abuse.

Standalone Weather Station, Part 1

Nearly The Same
Originally uploaded by hithisishal
Click image for more photos of this project

First, I have to put out a big thank you and acknowledgment to Jeff from mightyOhm. I saw a link to his wireless radio project posted somewhere, and thought it was interesting. I had not even heard of OpenWrt before reading the project on his blog. I began my work by reproducing his, then moving on. Similarly, if you are interested in building this, I recommend you begin by reading his tutorial, at least up to part 5.

Aside from radio functionality, one of the things that I would like to be able to do without a computer is check the weather in the morning. I use Weather Underground to check my weather - a neat, community based weather website with many features (including an API - more on that later). One of my favorite parts of this site is the simple statement under the 5-day forecast, along the lines of "Tomorrow is forecast to be Much Warmer than today." It would be useful to be able to view this statement without turning on my computer. Since it is such a small amount of information (only 5 different possibilities), it would be silly to dedicate complicated hardware to this. Instead, I will be displaying the result on an RGB LED (for now 2 LEDs) that fades between blue and red, based on the forecasted temperature relative to the past day.

I am developing this system using an ATMEGA168P, programmed in C. Excuse the appearance of my development hardware - it is not nearly as complicated as it looks. I'm simply using what I had available, which was originally constructed for a different purpose.

Software on the Router

First, I wrote a script for the router to check the forecast, and output the result as a number from 1 to 5. This would then be easy for the AVR to interpret. Since the router is considerably more powerful, it is logical to do as much processing on the router as possible. All of these scripts were written using vi, with a telnet connection to the router. To use this script, put this file in a location that the $PATH variable points to, such as /usr/bin/, and use chmod 577 to make it executable. Unfortunately, the statement that I want is not contained in the API output, so the script uses wget to extract the contents of the Weather Underground search result website. The rest of the script is beyond the scope of this post, but there is a lot of information about shell scripting available on the internet.

#! /bin/ash

#reltemp.sh

FORECAST=`wget -q -O - "http://www.wunderground.com/cgi-bin/findweather/getForecast?query=$ZIPCODE" | grep 'is forecast to' | sed 's/<[^>]*>//g;s/^ [ ]*//g' `

#echo $FORECAST

case $FORECAST in
"Tomorrow is forecast to be Much Warmer than today."|"Today is forecast to be Much Warmer than yesterday.")
echo 5
;;
"Tomorrow is forecast to be Warmer than today."|"Today is forecast to be Warmer than yesterday.")
echo 4
;;
"Tomorrow is forecast to be nearly the same temperature as today."|"Today is forecast to be nearly the same temperature as yesterday.")
echo 3
;;
"Tomorrow is forecast to be Cooler than today."|"Today is forecast to be Cooler than yesterday.")
echo 2
;;
"Tomorrow is forecast to be Much Cooler than today."|"Today is forecast to be Much Cooler than yesterday.")
echo 1
;;
*)
echo 0
;;
esac

Now, we have to set up our location in the environment variable ZIPCODE. Simply add the following line to the /etc/profile file, obviously with your own zip code.

export ZIPCODE=19104

With this complete, simply type reltemp.sh, and in a couple of seconds, a number between 1 and 5 should appear on the terminal, indicating the forecasted temperature of tomorrow relative to today, or today relative to yesterday, based on the time of day.

External Interface

Now, the AVR must talk to the router in order to display the information. Although not pictured, the hardware is relatively simple. The AVR must be connected to power (provided by the router), a 20 MHz crystal oscillator, and the serial Rx and Tx on the router. Additionally, connect the LEDs as shown in the schematic below. This is connected to the PWM output of the AVR, so that a high signal will turn the red LED on, and a low signal will turn the blue LED on. Therefore, changing the duty cycle of a wave applied between the LEDs allows them to fade between blue and red. Change resistor values as needed to balance the shades, based on the brightness of the LEDs.

LEDs
Originally uploaded by hithisishal

Please note, although we developed similar solutions in parallel, what I did is slightly different from what Jeff does in his parts 6 and 7. I used the default router baud rate of 115.2k, but communication was only stable if I ran the AVR with a baud rate of 110k. You might have to tweak this value for your router, or clock it down as shown at mightyOhm.

/*

Copyright: Hal Emmer 2008
License: Creative Commons Attribution-Noncommercial-Share Alike 3.0

For atmega168, at 20 MHz.

*/

#include <stdio.h>
#include <avr/io.h>
#include <avr/eeprom.h>
#include <ctype.h>
#include <avr/interrupt.h>

#define FOSC 20000000
#define BAUD 110000 //router is nominally 115.2k bps, communication is most stable at 110k bps.
#define MYUBRR FOSC/8/BAUD-1 //double speed
//#define MYUBRR

#define sbi(var, mask) ((var) |= (uint8_t)(1 << mask))
#define cbi(var, mask) ((var) &= (uint8_t)~(1 << mask))

#define STATUS_LED 0

#define BUFFERSIZE 80

volatile unsigned int global_time1;

//======================
//Define functions
//======================

static int uart_putchar(char c2, FILE *stream);
uint8_t uart_getchar(void);
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
void init(void);
void get_output(char *str);
void get_rel_temp(void);
//======================




int main (void)
{

init(); //Setup IO pins and defaults
printf("\nreltemp.sh\n");
while(1){

if (global_time1 >= 4578){ //4578 = 1 minute
global_time1 = 0;
get_rel_temp();

}
}
}

void init (void)
{
//1 = output, 0 = input
DDRB = 0b11101111; //PB4 = MISO
DDRC = 0b11111110; //
DDRD = 0b11111110; //PORTD (RX on PD0)

//USART Baud rate: 115200
UBRR0H = ((MYUBRR >> 8));
UBRR0L = MYUBRR;
UCSR0B |= (1<<RXEN0)|(1<<TXEN0);
UCSR0A |= (1<<U2X0); //double rate

stdout = &mystdout; //Required for printf init


/* Set up PWM (for fading LED)*/
DDRB |= (1 << 3); // OC1A (PB3),outputs
ICR1 = 20000; // TOP, set for 125Hz
OCR1A = 10000; // neutral/purple
TCCR1A = (1<<COM1A1)|(1<<WGM11); // Clear on compare, set at TOP
TCCR1B = (1<<WGM13)|(1<<WGM12)|(1<<CS11); // Timer 1 fast PWM mode 14 , /8 prescaler


/* Set up TOI on timer2 for task timing */
TCCR2B |= (1<<CS22)|(1<<CS21)|(1<<CS20); //Start Timer2 with 1/1024 prescaler.
TIMSK2 |= (1<<TOIE2); //enable timer2 overflow interrupt
TIFR2 |= (1<<TOV2); //clear the mask
sei();
}


static int uart_putchar(char c2, FILE *stream)
{
//if (c2 == '\n') uart_putchar('\r', stream);

loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c2;

return c2;
}


uint8_t uart_getchar(void)
{
while( !(UCSR0A & (1<<RXC0)) );
return(UDR0);
}



/* not used right now */
void get_output(char *str) {
unsigned char count;
for (count = 0; count < BUFFERSIZE; count++) {
str[count] = uart_getchar();
if (str[count] == '@' && str[count - 1] == 't')
break;
}
str[count - 5] = '\0';
}


void get_rel_temp(void){
char c = 0;

printf("\nreltemp.sh\n"); //as the router for the relative temperature
while(!isdigit(c)) //get a character until you get a digit
c = uart_getchar();
switch(c){
case '0':
OCR1A = 10000; // error / purple
break;
case '1':
OCR1A = 0; // much cooler / blue
break;
case '2':
OCR1A = 2500; // cooler / blue-purple
break;
case '3':
OCR1A = 10000; // same temp as / purple
break;
case '4':
OCR1A = 17500; // warmer / red-purple
break;
case '5':
OCR1A = 20000; // much warmer / red
break;
default:
OCR1A = 10000; // error / purple
break;
}
}

ISR(TIMER2_OVF_vect)
{
global_time1++;
//uart_putchar('0'+global_time1, stdout);
TIFR2 |= (1<<TOV2);

}

That should do it. Next time I will explore how to display the next important piece of information - if it will be sunny, cloudy, rainy, etc. After that I will wrap up the project in a more presentable package.