I2C TWI-MULTI.lib
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Latest revision as of 20:49, 17 January 2017
The I2C_TWI-MULTI library is intended to be used with normal AVR processors which have 2 or more TWI interfaces.
An example of such a processor is the ATMEGA328PB
In order to support multiple busses, this library need to be included using the $LIB directive.
Further you need to create a byte variable named _i2cchannel in your code.
This variable will hold the bus or TWI number.
By default it will be 0 and thus the usual TWI hardware will be used : Portc.5 and Portc.4
By setting the variable to 1, the second TWI hardware will be used : Porte.0 and Porte.1
Further you need to use CONFIG TWI1 instead of CONFIG TWI in order to specify the clock rate for the second TWI : Config Twi1 = 100000
All other code will remain compatible.
Example
'-------------------------------------------------------------------------------- 'name : m328pb.bas 'copyright : (c) 1995-2016, MCS Electronics 'purpose : demonstrates M328pb 'micro : Mega328pb 'suited for demo : yes 'commercial addon needed : no '-------------------------------------------------------------------------------- $regfile = "m328pbdef.dat" $crystal = 8000000 $baud = 19200 $hwstack = 40 $swstack = 40 $framesize = 40 ' USART TX RX ' 0 D.1 D.0 ' 1 B.3 B.4 ' ISP programming ' MOSI-PB3 MISO-PB4 SCK-PB5 ' TWI SDA SCL ' 0 C.4 C.5 ' 1 E.0 E.1 'Configuration Config Clockdiv = 1 'make sure we get 8 Mhz from internal osc Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0 Config Com2 = 19200 , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0 'we have 2 TWI interfaces Config Scl = Portc.5 ' we need to provide the SCL pin name Config Sda = Portc.4 ' we need to provide the SDA pin name Config Sda1 = Porte.0 'use this for the second TWI Config Scl1 = Porte.1 Config Twi = 100000 'speed 100 KHz Config Twi1 = 100000 'speed 100 KHz 'some constants for the signature row Const Device_signature_byte1 = 0 Const Device_signature_byte2 = 2 Const Device_signature_byte3 = 4 Const Rc_oscillator_calibration = 1 Const Serial_number_byte0 = &H0E Const Serial_number_byte1 = &H0F Const Serial_number_byte2 = &H10 Const Serial_number_byte3 = &H11 Const Serial_number_byte4 = &H12 Const Serial_number_byte5 = &H13 Const Serial_number_byte6 = &H14 Const Serial_number_byte7 = &H15 Const Serial_number_byte8 = &H16 Const Serial_number_byte9 = &H17 $lib "I2C_TWI-MULTI.lib" 'important for using 2 TWI interfaces Dim _i2cchannel As Byte ' you MUST dim this variable yourself when using the above lib Dim B As Byte 'just a used byte I2cinit 'default TWI init I2cinit Twi1 'optional specify TWI1 to init that interface Open "com2:" For Binary As #2 'create a channel to reference the UART 'print the chip ID Print "ID : " ; Hex(readsig(device_signature_byte1)) ; Hex(readsig(device_signature_byte2)) ; Hex(readsig(device_signature_byte3)) 'all I2C statements will work the same. All you need to do is to set the _i2cchannel variable to 0 or 1 _i2cchannel = 1 'try the second bus Print "Scan start" For B = 0 To 254 Step 2 'for all odd addresses I2cstart I2cwbyte B 'send address If Err = 0 Then 'we got an ack Print "Slave at : " ; B ; " hex : " ; Hex(b) ; " bin : " ; Bin(b) End If I2cstop 'free bus Next Do Print "COM1" Print #2 , "COM2" Waitms 1000 Loop
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