Serial transmission at 9600 bauds is possible with the Trinket ATtiny85 (5Volts, 8Mhz) from Adafruit.
The analog value (0~1023) presented at the analog pin 1 is serially transmited to the COM-11441 ( 7-segments Serial Display from Sparkfun).
The Sketch:
/* Pot_Display7_02.ino Arduining.com 20 JAN 2014 Serial transmission at 9600 bauds using bit banging.(Trinket (5V, 8mhz). Analog 1 in presented in the 7-Segment Serial Display COM-11441 from Sparkfun. Using delayMicroseconds() for serial timming. BITTIME = 93 was adjusted experimentally. */ //----- defining some values:------------------------------------------------- #define TXDATA 0 // Pin used to transmit data. #define POT 1 // pin used to read the analog value. #define BITTIME 93 // adjusted to obtain 104 milliseconds delay (9600bauds). //----------variables:-------------------------------------------------------- int potVal=0; //============================================================================ void setup() { pinMode(TXDATA, OUTPUT); // initialize the TXDATA pin as an output. digitalWrite(TXDATA,HIGH); // TXDATA = 5V when is resting. delay(10); //Wait for Serial Display startup. sendChar('v'); //Reset the display 0x76. } //---------------------------------------------------------------------------- void sendChar(char c){ delayMicroseconds(BITTIME*2); // wait 2 Stop bits before sending the char digitalWrite(TXDATA,LOW); // low the line delayMicroseconds(BITTIME); // wait Start bit for (int i=0; i<8;i++){ digitalWrite(TXDATA,bitRead(c, i)); // bit out. delayMicroseconds(BITTIME); // wait bit } digitalWrite(TXDATA,HIGH); //Return TXDATA pin to "1". } //------------------------------------------------------------------------- void show(String s){ for(int i=0;i<4;i++){ sendChar(s[i]); } } //========================================================================= void loop() { potVal= analogRead(POT); String strPot = String (potVal); while(strPot.length()<4)strPot= " " + strPot; //format to 4 characters. show(strPot); delay(100); }
Then the potentiometer is replaced by a keypad 3×4 and some resistors.
The resistor networw is designed to produce diferent voltage levels for each key pressed.
And this is the Sketch using the keypad:
/* AnalogKey_03.ino Arduining.com 23 JAN 2014 Using an analog pin to read a 3x4 keypad and presenting the keyed data in the 7-Segment Serial Display COM-11441 from Sparkfun. Notes: Implemented using the Arduino Trinket (5V, 8Mhz) from Adafruit. Serial transmission at 9600 bauds using bit banging. BITTIME delay was determined using an oscilloscope. 1% resistors are used in the keypad (1.62k,6.49k and 25.5k) */ //----- defining some values:------------------------------------------------- #define TXDATA 0 // Pin used to transmit data. #define ADIN 1 // pin used to read the analog value. #define BITTIME 93 // Adjusted experimentally to obtain 9600 bauds. #define DEBOUNCE 5 // number of detections before key validation. //----------variables:-------------------------------------------------------- int lastkey= -1; // No key. int key; // key value boolean released= true; // No key pressed estatus. boolean newline= true; // flag to clean screen before new value entry. int validkey=0; // used as debounce counter. int analog; // value of the analog pin. char dispbuff[]= "- "; //============================================================================ void setup() { pinMode(TXDATA, OUTPUT); // initialize the TXDATA pin as an output. digitalWrite(TXDATA,HIGH); // TXDATA = 5V when is resting. delay(10); //Wait for Serial Display startup. sendChar('v'); //Reset the display 0x76. } //---------------------------------------------------------------------------- void sendChar(char c){ delayMicroseconds(BITTIME*2); // wait 2 Stop bits. digitalWrite(TXDATA,LOW); // TXDATA=0. delayMicroseconds(BITTIME); // wait Start bit. for (int i=0; i<8;i++){ digitalWrite(TXDATA,bitRead(c, i)); // bit out. delayMicroseconds(BITTIME); // wait bit } digitalWrite(TXDATA,HIGH); //TXDATA=1. } //-------------------------------------------------------------------------- void show(String s){ for(int i=0;i<4;i++){ sendChar(s[i]); } } //-------------------------------------------------------------------------- void checkey(){ analog= analogRead(ADIN); key=-1; // no key pressed. if(analog<524) key=1; if(analog<508) key=4; if(analog<491) key=7; if(analog<472) key=10; // '*' key if(analog<453) key=2; if(analog<432) key=5; if(analog<409) key=8; if(analog<385) key=0; if(analog<359) key=3; if(analog<330) key=6; if(analog<299) key=9; if(analog<265) key=11; // '#' key if (key!=lastkey){ validkey=0; lastkey=key; } validkey++; if(validkey > DEBOUNCE){ validkey=0; if (key<0){ released= true; return; } else if (released == true){ released=false; return; } } key=-1; } //-------------------------------------------------------------------------- void clrbuff(){ dispbuff[0]= '-'; dispbuff[1]= ' '; dispbuff[2]= ' '; dispbuff[3]= ' '; newline= false; } //-------------------------------------------------------------------------- void action(){ dispbuff[0]= 'd'; dispbuff[1]= 'o'; dispbuff[2]= 'n'; dispbuff[3]= 'e'; newline= true; } //========================================================================== void loop() { show(dispbuff); //Show content of the array dispbuff in the display checkey(); if(key>=0){ if(key==10) clrbuff(); if(key==11) action(); if(key<10){ if (newline==true) clrbuff(); dispbuff[0]= dispbuff[1]; //buffer shift (display shift to the left) dispbuff[1]= dispbuff[2]; dispbuff[2]= dispbuff[3]; dispbuff[3]=char(key+'0'); } } delay(5); // experimental, 5 works fine. (10 is to slow). }
The video is in YouTube:
Arduining 
e super mar interesa codul sursa
The code was added, thanks for asking.