© MCS Electronics, 1995-2007

Compare1a = W

W = Compare1a

'And the TIMER can be used in PWM mode

'You have the choice between 8,9 or 10 bit PWM mode

'Also you can specify if the counter must count UP or down after a match 'to the compare registers

'Note that there are two compare registers A and B

Config Timer1 = Pwm , Pwm = 8 , Compare A Pwm = Clear Up , Compare B Pwm = Clear Down , Prescale = 1

'to set the PWM registers, just assign a value to the compare A and B registers

Compare1a = 100

Compare1b = 200

'Or for better reading :

Pwm1a = 100

Pwm1b = 200

End

CONFIG TIMER2

Action

Configure TIMER2.

Syntax for the 8535

CONFIG TIMER2 = TIMER | PWM , ASYNC=ON |OFF,

PRESCALE = 1 | 8 | 32 | 64 | 128 | 256 | 1024 ,

COMPARE = CLEAR | SET | TOGGLE I DISCONNECT ,

PWM = ON | OFF ,

COMPARE PWM = CLEAR UP| CLEAR DOWN | DISCONNECT ,

CLEAR TIMER = 1|0

Syntax for the M103

CONFIG TIMER2 = COUNTER| TIMER | PWM ,

EDGE= FALLING |RISING,

PRESCALE = 1 | 8 | 64 | 256 | 1024 ,

COMPARE = CLEAR | SET | TOGGLE I DISCONNECT ,

PWM = ON | OFF ,

COMPARE PWM = CLEAR UP| CLEAR DOWN | DISCONNECT ,

CLEAR TIMER = 1|0

Remarks

The TIMER2 is an 8 bit counter.

It depends on the chip if it can work as a counter or not.

The syntax shown above must be on one line. Not all the options need to be selected.

Here is the effect of the various options.

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© MCS Electronics, 1995-2007

'Twbr = 12 'bit rate register 'Twsr = 0 'pre scaler bits

Dim B AsByte, X AsByte

Print"TWI master"

Do

Incr B ' increase value

I2csend&B01110000 , B ' send the value

Print"Error : ";Err' show error status

I2creceive&B01110000 , X ' get a byte

Print X ;" ";Err' show error

Waitms 500 'wait a bit

Loop

End

CONFIG TWISLAVE

Action

Configure the TWI Slave address and bitrate

Syntax

CONFIG TWISLAVE = address , BTR = value , BITRATE = value SAVE=option

Remarks

The variables Twi , Twi_btr and Twi_btw are created by the compiler. These are all bytes The TWI interrupt is enabled but you need to enabled the global interrupt

The TWI Slave code is running as an interrupt process. Each time there is a TWI interrupt some slave code is executed. Your BASIC code is called from the low level slave code under a number of events. You must include all these labels in your Slave application. You do not need to write code in all these sub routines.

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The TWI Slave code will save all used registers. But as it will call your BASIC application as the TWI interrupt occurs, your BASIC code could be in the middle of a PRINT statements. When you then execute another PRINT statement , you will destroy registers.

So keep the code in the sub routines to a minimum, and use SAVE option to save all registers.

While two printing commands will give odd results (print 12345 and 456 in the middle of the first print will give 1234545) at least no register is destroyed.

See also

CONFIG TWI

ASM

NONE

Example

'-------------------------------------------------------------------------------

' (c) 1995-2006 MCS Electronics

'This demo shows an example of the TWI in SLAVE mode

'This demo is a Mega8 I2C A/D converter slave chip

'NOTICE that this demo will only work with the TWI slave library which is avaialble as an add on

'SDA pin is PORTC.4 (pin 27)

'SCL pin is PORTC.5 (pin 28)

Print"MCS Electronics M8 TWI-slave demo"

Print"Use with M8-TWI master demo"

Config Adc = Single ,Prescaler = Auto 'Now give power to the chip

StartAdc

Dim W As Word

Config Portb= Output

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© MCS Electronics, 1995-2007

Config Twislave = &H70 ,Btr= 2,Bitrate= 100000

'^---slaveaddress

'The TWI interrupt is enabled but you need to enabled the global interrupt

EnableInterrupts

'this is just an empty loop but you could perform other tasks there

Do

'Print Getadc(0) 'Waitms 500 nop

Loop

End

'The following labels are called from the library. You need to insert code in these subroutines 'Notice that the PRINT commands are remarked.

'You can unmark them and see what happens, but it will result in occasional errors in the transmission 'The idea is that you write your code in the called labels. And this code must execute in as little time 'as possible. So when you slave must read the A/D converter, you can best do it in the main program

'then the data is available when the master needs it, and you do not need to do the conversion which cost time.

'A master can send or receive bytes.

'A master protocol can also send some bytes, then receive some bytes 'The master and slave must match.

'the following labels are called from the library when master send stop or start Twi_stop_rstart_received:

' Print "Master sent stop or repeated start"

Return

'master sent our slave address and will not send data Twi_addressed_goread:

' Print "We were addressed and master will send data"

Return

Twi_addressed_gowrite:

' Print "We were addressed and master will read data"

Return

'this label is called when the master sends data and the slave has received the byte 'the variable TWI holds the received value

Twi_gotdata:

' Print "received : " ; Twi ; " byte no : " ; Twi_btw

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