Yes, there are 5! I'm sending the number first so the Arduino's know which to apply commands to, and which heater's data they receive. I thought that immediate feedback is not needed as 1 minute later I will know if command took. Thing are not critical enough to require millisecond feedback.
What protocol change are you referring to? I thought that if you sent the device number first the Arduino then would be able to apply to the proper device. I'm a noob, trying to learn, I want to learn proper technique!
I'm hoping to do this as winter temperatures drop to as low as -25F here at 8000 ft. I'm going down to Denver for a few days so further responses will be slow.

Jim

The slave has an RTC, and sends data once a minute in ASCII. Message protocol is :
---------------------------
slave transmits

ff hex - begin transmission
heater number - 1
ff hex - separator
heater 1 temp
ff - separator
heater 1 status - off/on/faulted
ff - separator
....
heater number  - n
ff - separator
heater n temp
ff - separator
heater n status
00 hex - end of transmission

---------------------------------
master sends on keypress

ff hex - begin command
heater number - 1
ff - separator
heater 1 on/off command
ff - separator
....
heater number - n
ff - separator
heater number n on/off command
00 hex - end of transmission
 --------------------------------

The master also has an RTC and a data logger logging the slave's data. Any heater faulted will be automatically shut down.

Jim

I need to remotely control heaters and monitor temperatures remotely from about 80 ft. from the house. I'd like to not have a PC involved for power reasons. I planed for the master Arduino to have an LCD display for monitoring and a keypad to command heaters on/off. I've found information on transmitting from an APC220, but nothing on receiving commands from one, or data. Is this a possibility, or am I dreaming? I have 2 Uno's and 2 APC220's, the keypad and LCD and the temperature and relay modules already. I wrote a sketch for the temp and control of heaters, now I just need to get the Uno's talking to each other.
Jim

I need to monitor 3 DC voltages that switch from + 12  volts to - 12 volts, DC. What I'm doing is monitoring 3 fuses to shut things down if one blows (ie. across the fuse suddenly measures 12 Volts ). I know a divider works to reduce to 12v to 5v, but with an Arduino I need to have always have a positive voltage for the Arduino to measure. What I really need is to just verify the presence of the voltages.  Best would be if it could be isolated somehow before the Arduino sees it (optical ?). I would really like this to be in the form of a shield or brick as I'm handicapped and only have use of one hand. Does anything meet these requirements?

Jim

terryking228, these pages are really helpful and quite detailed. However the brick I've been having troubles with is the Sensor brick shown at the bottom of page http://arduino-info.wikispaces.com/Brick-Temperature-DS18B20. Some work, some don't and i don't know why. I bought a batch of 5, and only three 3 work.

Jim

Thanks maniacbug, I have a problem with the ;'s because Quickbasic(the only language I sort know) does not require them. I commented out the other line and it compiles without error. Now I'll work on inserting the "F".

Jim

I trying to display temperature and humidity on a LCD48

Code:

84 module. the temperature reading function returns a float, the lcd module expects a string. The floatToString function returns the result as char * name. My code is thus:

[code]#include "LCD4884.h"
#include "DFrobot_bmp.h"
#include <SHT1x.h>

#define dataPin  10   // DATA
#define clockPin 11   // SCK
SHT1x sht1x(dataPin, clockPin);

 #include "floatToString.h"  //set to whatever is the location of floatToStrig



// menu starting points

#define MENU_X 10 // 0-83
#define MENU_Y 1 // 0-5


int  adc_key_val[5] ={50, 200, 400, 600, 800 };




void setup(){
  lcd.LCD_init();
  lcd.LCD_clear();
  Serial.begin(9600);
}
/* loop */

void loop()
{
  float temp_f;
  float humidity;


  // Read values from the sensor
  char tempString[25]; // just give it plenty to write out any values you want to test
  temp_f = sht1x.readTemperatureF();
  Serial.println("floatToString(tempString, temp_f , 4);");
  tempString += " F"
  lcd.LCD_write_string_big(15,1,tempString,MENU_NORMAL);*/

  humidity = sht1x.readHumidity();
//  lcd.LCD_write_string_big(15,1,
}

The error I get is:

TEMP_HUM_LCD.cpp: In function 'void loop()':
TEMP_HUM_LCD:40: error: invalid operands of types 'char [25]' and 'const char [3]' to binary 'operator+'
TEMP_HUM_LCD:40: error: in evaluation of 'operator+=(char [25], const char [3])'
TEMP_HUM_LCD:41: error: expected `;' before 'lcd'
TEMP_HUM_LCD:41: error: expected primary-expression before '/' token

I'm still a newbie, unsure of where to go from here!

Jim[/code]

Of all the things you would never suspect, I had a bad USB cable.

Jim

When I get this kind of avrdude errors I always check if I selected the right board and comport under the tools menu. If OK then I disconnect the Arduino for 5 seconds so the OS can refresh its internal administration..

I'm in the house right now, I try this when I go back to my observatory. Thanks!

Jim

I²C is designed for chaining - just connect both devices to the SDA and SCK lines, and make sure they have nonconflicting addresses.

Thanks for the reply! How does the Arduino specify the device address? I assume that means I could stack I²C shields by just giving them different addresses.

Jim

When this error message is printed, it is accompanied by a link to the Troubleshooting section. What steps have you tried there? With what results?

Typical errors are not selecting the right board and/or the right port, in the Tools menu.

The code does not get loaded on the shield. Are you able to upload code to the Arduino without the shield attached?

These are the error messages exactly as received(copied from the information line).
I loaded a test sketch to the board and it ran perfectly(blinking led).

Jim

What is i2r?
I2c, spi, serial?

of course I meant i2c, sorry.

Jim

I thinking of a project where I'll need a Wifi shield and a LCD shield both running together. Is this possible and if so, how?

Jim

I just bought a "LinkSprite CuHead WiFi Shield for Arduino" from CuteDigi. I am attempting to test it as described in the wiki page http://asynclabs.com/wiki/index.php?title=AsyncLabsWiki. I downloaded the library and installed it as directed and pulled in the WebServer example. It compiles just fine, but after downloading to the Arduino I get the error message:

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

The only modifications I have made to the sketch is entering my SSID and passwords. My Arduino is a Duemilanove. Anyone, any ideas?

Jim

Oh, so the products from http://www.emartee.com/

You will find documentation (such as it is) on that site.

Yep, that is just what I'm talking about. That is as uninformative as can be for a newbie. Information varies from fair to none depending on the board. Code examples are few. Many are manufactured by others. maybe THEY should provide more information. I have two of the "switch brick V2", one works, one does not. From inspecting the board back lit with a bright light, it's not clear how it is working.

Jim