Code Body

To use this file copy and paste this: // #URL-lib "http://pin1.org/forthlib/flb/I2C/i2c.flb" into BV Terminal 3 or here to download.

// HISTORY:
// Aug 2007 *updated by adding a few extra words
//          *added a section at the back
// Oct 2007 *error with P, should not use i2-valid (corrected)
//          *added libaraies
// Dec 2007 *loader added
//          *sid used in loader-1
// Feb 2008 *this file is now a library with
//          *only the public words exposed
// Nov 2008 *Renamed the AA,SI,STO & STA constants to prevent
//           clashes when using with sid=0
//          *Increased number of re-tries on i2-start to cater for
//           slow devices

// REQUIRES: // #URL-lib "http://pin1.org/forthlib/flb/General/soft1.flb" sid=0 // #URL-lib "http://pin1.org/forthlib/flb/General/pinsel.flb" sid=101

// Register CONSTANTS: // channel 0 - only channel 0 used, there is a channel 1, extend // this file as required. &E001C000 constant I2CONSET &E001C004 constant I2STAT &E001C008 constant I2DAT &E001C00C constant I2ADR // not used &E001C010 constant I2SCLH &E001C014 constant I2SCLL &E001C018 constant I2CONCLR // easier to understand 4 constant I2_AA 8 constant I2_SI 16 constant I2_STO 32 constant I2_STA

Full Contents of File

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// I2C interface
// Uses the built in I2C functionality of the LPC2xxx
// This is the generic I2C driver with ARM as the master
// To drive individual devices
// NOTE: This file only makes use of I2C channel 0, there is
// another channel but it is not implemented here
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

// HISTORY:
// Aug 2007 *updated by adding a few extra words
// *added a section at the back
// Oct 2007 *error with P, should not use i2-valid (corrected)
// *added libaraies
// Dec 2007 *loader added
// *sid used in loader-1
// Feb 2008 *this file is now a library with
// *only the public words exposed
// Nov 2008 *Renamed the AA,SI,STO & STA constants to prevent
// clashes when using with sid=0
// *Increased number of re-tries on i2-start to cater for
// slow devices

// REQUIRES:
// #URL-lib "http://pin1.org/forthlib/flb/General/soft1.flb" sid=0
// #URL-lib "http://pin1.org/forthlib/flb/General/pinsel.flb" sid=101

// Register CONSTANTS:
// channel 0 - only channel 0 used, there is a channel 1, extend
// this file as required.
&E 0 0 1 C 0 0 0 c o n s t a n t I 2 C O N S E T
&E 0 0 1 C 0 0 4 c o n s t a n t I 2 S T A T
&E 0 0 1 C 0 0 8 c o n s t a n t I 2 D A T
&E 0 0 1 C 0 0 C c o n s t a n t I 2 A D R // not used
&E 0 0 1 C 0 1 0 c o n s t a n t I 2 S C L H
&E 0 0 1 C 0 1 4 c o n s t a n t I 2 S C L L
&E 0 0 1 C 0 1 8 c o n s t a n t I 2 C O N C L R
// easier to understand
4 c o n s t a n t I 2 _A A
8 c o n s t a n t I 2 _S I
1 6 c o n s t a n t I 2 _S T O
3 2 c o n s t a n t I 2 _S T A

// Set I2C frequency in Hz, this is for starters and can be changed
// by the public word at the end of the file
5 0 0 0 0 c o n s t a n t i 2 c B u s S p e e d // conservative

// run this first to set up hardware
// (---)
: i2c-init
2 1 p i n s e l e c t // set i2c functions
3 1 p i n s e l e c t // on pins p0.2 and p0.3
p c l k i 2 c B u s S p e e d / // I2C speed
d u p I 2 S C L H ! I 2 S C L L ! // 75khz @ plck = 60Mhz
&4 0 I 2 C O N S E T ! // enable i2c
;

// enables speed to be set after initialisation
// set speed in Hz, i.e 100000 = 100kHz
// ( speed ---)
: i2-speed
p c l k s w a p / dup
I 2 S C L H ! I 2 S C L L !
;

// send start condition return true if master can
// take charge of bus, otherwise returns 0
// ( --- -1|0)
: i2-start
0
1 0 0 0 0 f o r
I 2 _S T A I 2 C O N S E T ! // start
I 2 S T A T @ &0 8 = i f d r o p -1 l e a v e t h e n
n e x t
;

// when a command is issued the status goes to &f8
// this can keep the command here until its finished
// the time out of 100000 should be long enough for the slowest of
// i2c devices. It is about 300ms
: i2-valid
1 0 0 0 0 0
f o r
i 2 s t a t @ &f 8 <> i f l e a v e t h e n
n e x t
;

// Checks status of I2c device with timeout, if
// no agreement will abort, otherwise continues
// ( stat ---)
: i2-stat
i 2 s t a t @ 2 d u p <>
i f
c r ." i 2 c E r r o r - S t a t u s r e c i e v e d " p h . ." E x p e c t i n g " p h .
a b o r t
e l s e
2 d r o p
t h e n
;

// I2c data register for putting and fetching the data
: i2-dat@i 2 d a t @ ; // ( --- data)
: i2-dat!i 2 d a t ! ; // ( data ---)

// In general i2c3 will do as a stop condition, but not always
// these commands take a finite time to establish, and when they are
// not ready the status is &f8, i2-valid returns when these commands
// return a valid state or a time out occures
// conditions, see datasheet STA ST0 SI AA
: i2c1 I 2 _S T A I 2 _S T O + I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ; // 0 0 0 x
: i2c2 I 2 _S T A i 2 c o n s e t ! I 2 _S T O I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ; // 1 0 0 x
: i2c3 I 2 _S T O i 2 c o n s e t ! I 2 _S T A I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ; // 0 1 0 x
: i2c4 I 2 _S T A I 2 _S T O + i 2 c o n s e t ! I 2 _S I i 2 c o n c l r ! i 2 -v a l i d ; // 1 1 0 x
: i2c5 I 2 _S T A I 2 _S T O + I 2 _S I + I 2 _A A + i 2 c o n c l r ! i 2 -v a l i d ; // 0 0 0 0
: i2c6 I 2 _A A i 2 c o n s e t ! I 2 _S T A I 2 _S T O + I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ;
// 0 0 0 1
//
: i2-8 i 2 d a t ! I 2 _S T O I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ; // ( device-address --- )
: i2-10 i 2 d a t ! I 2 _S T O I 2 _S I + i 2 c o n c l r ! i 2 -v a l i d ; // ( device-address --- )

// **************************************************************
// The following uses the above to create an I2C interface
// **************************************************************
// Example
// To write to a simple device address &50
// &50 s ; start and sends address
// 12 i2-sb ; send byte
// p ; stop
// To read
// &51 s
// i2-rn
// i2-rl ; lasyt byte ** bus will hang if not used
// p

// Start and send address
// ( address ---)
: (s)
i 2 -s t a r t 0 = a b o r t " E r r o r I 2 C c a n t s t a r t "
i 2 s t a t @ &8 = i f i 2 -8 e s c a p e t h e n
i 2 s t a t @ &1 0 = i f i 2 -1 0 e s c a p e t h e n
." E r r o r s t a r t r e t u r n s " i 2 s t a t @ p h .
." a s s t a t u s v a l u e "
;

// =================== Public interface ==========================
// Stop - should return &f8 as a status but may need
// a small amount of time to do this.
: <0>p I 2 _S T O i 2 c o n s e t ! I 2 _S T A I 2 _S I + i 2 c o n c l r ! // i2c3 without valid checkg
-1
1 0 0 0 0 0
f o r
i 2 s t a t @ &f 8 =
i f
1 + l e a v e
t h e n
n e x t
i f
." I 2 C S t o p e r r o r "
t h e n
;

// Start and send address
// ( address ---)
: <0>s
(s) // check if device exists & bus okay
i 2 s t a t @ // should not be 38,48,or 0x58
d u p &3 8 = s w a p d u p &4 8 = s w a p &5 8 = o r o r
i f ." D e v i c e d o e s n o t a c k n o w l e d g e " p t h e n
;

// repeated start
// ( address ---)
: <0>rs
i 2 c 2 i 2 s t a t @ &1 0 =
i f
i 2 -1 0
e l s e
." R e p e a t e d s t a r t e r r o r "
t h e n
;

// send next byte, no need for last byte
// ( data ---)
: <0>sb
i 2 d a t !
i 2 c 1
;

// read next byte
// ( --- data)
: <0>rn
i 2 c 6 &5 0 i 2 -s t a t
i 2 -d a t @
;

// read last byte - does not do stop
// ( --- data)
: <0>rl
i 2 c 5 &5 8 i 2 -s t a t
i 2 -d a t @
;

: <0>I2-init ( -- ) i 2 c -i n i t ;
: <0>i2Speed ( Hz -- ) I 2 -s p e e d ;