LeafLabs Garden » Topic: Maple i2c with Arduino

LeafLabs Garden » Topic: Maple i2c with Arduino http://forums.leaflabs.com/topic.php?id=10041 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:26:54 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php _Jesmeister_ on "Maple i2c with Arduino" http://forums.leaflabs.com/topic.php?id=10041#post-21908 Mon, 07 Jan 2013 21:00:30 +0000 _Jesmeister_ 21908@http://forums.leaflabs.com/ gbulmer: I may not have been clear on the "transferring only once". The Arduino will correctly receive one transfer from the Maple, but subsequent transfer attempts fail. This should answer your second question too. The code above underneath "Arduino Slave" is the Arduino code. I'm not sure that I understand your third comment, but looking at the wire library (<a href="http://leaflabs.com/docs/libs/wire.html#libs-wire" rel="nofollow">http://leaflabs.com/docs/libs/wire.html#libs-wire</a>) I use the endTransmission() function to find the return value. That return value is 0 when I first upload the sketch to the maple. It will make one successful transfer to the Arduino upon which the return value of endTransmission(); becomes a 2. As I am reading and according to the i2c.h file a 2 indicates: ENACKADDR: Did not receive ACK on transmit of address. No bytes are actually sent when this happens. To account for the differing voltage levels, I believe that 3.3V should still be high enough to trigger a HIGH input voltage on the Arduino (I am getting one valid transfer). I did, however, wire up some 5V pull ups on the I2C lines just to be sure and that was not the problem. It still exhibited the same behavior. I have also wired up the maple to an oscilloscope and it is definitely attempting a transfer whenever I ask it to. gbulmer on "Maple i2c with Arduino" http://forums.leaflabs.com/topic.php?id=10041#post-21905 Mon, 07 Jan 2013 17:37:16 +0000 gbulmer 21905@http://forums.leaflabs.com/ _Jesmeister_ - I think your assumption "when I use the maple I can only successfully transfer once." may be incorrect. From your list of symptoms, the Arduino never responds in any way. Is that correct? You do not mention any code running on the Arduino which indicates it has received anything, so I assume not. If you assume that the Arduino never detected or received a message, and hence never attempts to respond, the symptoms still look consistent. Maple signals are 0v to 3.3V and Arduino 0v to 5V. How are you accounting for the different voltage levels between the two devices? _Jesmeister_ on "Maple i2c with Arduino" http://forums.leaflabs.com/topic.php?id=10041#post-21899 Mon, 07 Jan 2013 13:04:18 +0000 _Jesmeister_ 21899@http://forums.leaflabs.com/ I'm at a loss here. Any help would be greatly appreciated. I'm attempting to use a Maple leaf board (rev5) as an I2C master that interfaces with an Arduino (any board) acting as an I2C slave. I've swapped out a second Arduino for the Maple and the code seems to work. However, when I use the maple I can only successfully transfer once. By transfer once, I mean that the communication seems to stop after the first successful Wire.endTransmission(). Through troubleshooting here is what I've found so far. 1. When not connected to any device the return value of Wire.endTransmission(); is 0, which according to the maple documentation says the transfer was successful. 2. The maple must be rebooted to make another transfer. 3. rebooting the Arduino does not seem to make a difference. 4. After the first successful transfer from the maple the return value of Wire.endTransmission(); is = 2. That means that the slave is not sending an ACK upon its address being sent. 5. 5V pull ups on the Arduino did not do anything. The only thing I can think is that there is some difference in the lower level protocol between the maple and the Arduino. Any ideas? Here's the relevant codes: Maple Master: <code> if(z_pos != z_pos_old){ SerialUSB.print(z_pos); Wire.beginTransmission(5); byte1 = z_pos & 255; byte2 = z_pos >> 8; Wire.send(byte1); // sends one byte Wire.send(byte2); // sends one byte rtnval = Wire.endTransmission(); // stop transmitting SerialUSB.print(" return value = "); SerialUSB.println(rtnval); } </code> Arduino slave <code> #include <Wire.h> int byte1, byte2; void setup() { Wire.begin(5); // join i2c bus with address #4 Wire.onReceive(receiveEvent); // register event Serial.begin(9600); // start serial for output } void loop() { delay(1000); Serial.println("waiting"); } // function that executes whenever data is received from master // this function is registered as an event, see setup() void receiveEvent(int howMany) { int x = Wire.available(); Serial.print("available: "); Serial.print(x); byte1 = Wire.read(); // receive byte as an integer byte2 = Wire.read(); byte2 = byte2 << 8; byte2 = byte2 + byte1; Serial.print (" position: "); Serial.println(byte2); x = Wire.available(); Serial.print("available: "); Serial.print(x); Wire.begin(5); } </code>