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"Everything is better with bluetooth "....
When I was testing the glass scale performance on the CNC machine a major annoyance was that I had to be very still, because the floor would flex when I leaned sideways. That made it very difficult to read the display of the computer with the data I was looking for. There has to be a better way - such as looking at the data on your cell phone.
So here we will add a bluetooth transceiver.
The transceiver I picked is a HC05.
The connection is pretty simple. Attention should be paid to use the 5V supply for Vcc:
The updated pin assignment is this:
Usage Pin (Arduino/PIC) Notes
------------------------------------------------------------------ REF 0/RB5 AM2303 1/RB7 BMP180 2/RB8 all I2C devices - not just BMP any more BMP180 3/RB9 all I2C devices - not just BMP any more USB+ 4/RB10 USB- 5/RB11 6/RB13 7/RB14 8/RB15 9/RA0 HC05/TXD 10/RA1 MEAS1 11/RB0 LED4 12/RB1 LED3 MEAS2 13/RB2 LED2 MEAS3 14/RB3 LED1 CLOCK 15/RA2 16/RA3 HC05/EN 17/RB4 HC05/RXD 18/RA4And so the only code changes are a library to drive the HC05 and an occasional output of the data to the bluetooth device. The immediate goal is not to output all the data via bluetooth but only an occasional snapshot.
Since it basically shows up as a serial port on both ends we need a way to read that on the target device. Here you can see the data piping into the PC via the USB bus and at the same time into an android phone via terminal emulator.
That worked as a first test, but the format is not very human-readable. So for now I will change the format of the data coming in though bluetooth to this:
1x: 1000.00 nm 2x: 500.00 nm 4x: 250.0 nm
since the board has no way of knowing what type of interferometer is set up.
[Update: this code has now been commented out. Instead we are duplicating the data stream that goes out the USB serial connection.]
In the future, it seems possible to ditch the USB cable altogether. A PC with bluetooth will see the HC05 as a com port just like the USB right now. At least in principle the computer should be able to read the data through bluetooth just as well as through USB. That would be very nice, since power could be supplied by the 15V supply on the laser.
Initialization of the HC05 is a bit tricky. That is because in the AT command code it can be set to different baud rates, depending on how it was powered up. So if a new baud rate is programmed in and the firmware does not know about it, the device may not function.
According to (note that Pin 34 is connected to EN for this module.)
http://www.martyncurrey.com/arduino-with-hc-05-bluetooth-module-at-mode/
"To activate AT mode on the HC-05 zs-040 modules we can:
– 1. Hold the small button switch closed while powering on the module.
– 2. Set pin 34 HIGH (3.3v) when power on.
– 3. Close the small push button switch after the HC-05 is powered.
– 4. Pull pin 34 HIGH after powering the HC-05.
Method 1.
Enters AT mode with the built in AT mode baud rate of 38400. The baud rate cannot be changed by the user.
This method allows the module to enter AT mode on start but but does not keep pin 34 HIGH and uses the “mini” AT mode.
Method 2.
Enters AT mode with the built in AT mode baud rate of 38400. The baud rate cannot be changed by the user.
If you keep pin 34 HIGH you will enable the “full” AT mode which allows all AT commands to be used.
If you let pin 34 return LOW after power on then “mini” AT mode will be enabled.
Method 3.*
Enters “mini” AT mode using the user defined communication mode baud rate.
Method 4.*
Enters “full” AT mode using the user defined communication mode baud rate.
If pin 34 is kept HIGH then the HC-05 enters the “full” AT mode. If pin 34 is brought HIGH and returned to LOW it will put the module in to “mini” AT mode."
We cannot programmatically push the small button while powering on the module.
We cannot drive the module off of the 3.3V line and that is why it is permanently connected to 5V.
so that only leaves the method 4. So if the HC05 comes from a different project you may have to reprogram the baud rate first..
http://www.comm2excel.com/projects/bluetooth_AT_Commands.php?id=17#
has a nice description of the available commands:
COMMAND FUNCTION 1 AT Test UART Connection 2 AT+RESET Reset Device 3 AT+VERSION Querry firmware version 4 AT+ORGL Restore settings to Factory Defaults 5 AT+ADDR Query Device Bluetooth Address 6 AT+NAME Query/Set Device Name 7 AT+RNAME Query Remote Bluetooth Device’s Name 8 AT+ROLE Query/Set Device Role 9 AT+CLASS Query/Set Class of Device CoD10 AT+IAC Query/Set Inquire Access Code 11 AT+INQM Query/Set Inquire Access Mode 12 AT+PSWD Query/Set Pairing Passkey 13 AT+UART Query/Set UART parameter 14 AT+CMODE Query/Set Connection Mode 15 AT+BIND Query/Set Binding Bluetooth Address 16 AT+POLAR Query/Set LED Output Polarity 17 AT+PIO Set/Reset a User I/O pin 18 AT+MPIO Set/Reset multiple User I/O pin19 AT+MPIO? Query User I/O pin 20 AT+IPSCAN Query/Set Scanning Parameters 21 AT+SNIFF Query/Set SNIFF Energy Savings Parameters 22 AT+SENM Query/Set Security & Encryption Modes 23 AT+RMSAD Delete Authenticated Device from List 24 AT+FSAD Find Device from Authenticated Device List 25 AT+ADCN Query Total Number of Device from Authenticated Device List26 AT+MRAD Query Most Recently Used Authenticated Device27 AT+STATE Query Current Status of the Device 28 AT+INIT Initialize SPP Profile 29 AT+INQ Query Nearby Discoverable Devices 30 AT+INQC Cancel Search for Discoverable Devices 31 AT+PAIR Device Pairing 32 AT+LINK Connect to a Remote Device 33 AT+DISC Disconnect from a Remote Device 34 AT+ENSNIFF Enter Energy Saving mode 35 AT+EXSNIFF Exit Energy Saving modeMore details available here:
http://wiki.iteadstudio.com/Serial_Port_Bluetooth_Module_(Master/Slave)_:_HC-05
So now the interferometer has bluetooth.
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