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Forum Index : Microcontroller and PC projects : I2C vs I2C2 vs I2C3

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elk1984

Senior Member

Joined: 11/07/2020
Location: United Kingdom
Posts: 228

Posted: 04:23pm 06 Nov 2020

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This may be a stupid question, but what was the reasoning behind using I2C2 and I2C3 as commands rather than extending the I2C command to accept a <port> parameter? Wouldn't combining and changing the parameters on the I2C command free up two tokens for other BASIC keywords?

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 01:49am 08 Nov 2020

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Like many things MMBasic, it just grew over time.

While testing the HT mouse versus my Arduino version, I needed a simple way the swap I2C ports so came up with this SUB

SUB I2Cx p%, I2Ccmd$
SELECT CASE p%
CASE 1
EXECUTE "I2C "+I2Ccmd$
CASE 2
EXECUTE "I2C2 "+I2Ccmd$
CASE 3
EXECUTE "I2C3 "+I2Ccmd$
END SELECT
END SUB

The full test program which has been tested on ports 1 and 2

' ht_mouse test
CLS
MODE 1
mousePort = 2
initmouse
SPRITE LOAD "mouse.spr",1
'pause 100
DO
readmouse
TEXT 0,0,STR$(x,6,0," ")+STR$(y,6,0," ")+STR$(lb,2,0," ")+STR$(rb,2,0," ")+STR$(sb,2,0," ")+STR$(xs,4,0," ")+STR$(ys,4,0," ")+STR$(ss,6,0," ")
SPRITE SHOW 1,x,y,1
PAUSE 30
LOOP UNTIL INKEY$ <>""
SPRITE HIDE 1
I2Cx mousePort, "CLOSE"
'
SUB initmouse
I2Cx mousePort, "OPEN 100,1000"
I2Cx mousePort, "WRITE 41,0,3,20,INT(MM.HRES \ 256),INT(MM.HRES MOD 256)"
I2Cx mousePort, "WRITE 41,0,3,20,INT(MM.HRES \ 256),INT(MM.HRES MOD 256)"
I2Cx mousePort, "WRITE 41,0,3,22,INT(MM.VRES \ 256),INT(MM.VRES MOD 256)"
I2Cx mousePort, "WRITE 41,0,3,24,INT(MM.HRES \ 512),INT((MM.HRES\2) MOD 256)"
I2Cx mousePort, "WRITE 41,0,3,26,INT(MM.VRES \ 512),INT((MM.VRES\2) MOD 256)"
I2Cx mousePort, "WRITE 41,0,2,28,10"
END SUB
'
SUB readmouse
DO
I2Cx mousePort, "WRITE 41,1,1,0"
I2Cx mousePort, "READ 41,0,10,s$"
x=STR2BIN(UINT16,LEFT$(s$,2),big)
y=STR2BIN(UINT16,MID$(s$,3,2),big)
lb=ASC(MID$(s$,5,1))
rb=ASC(MID$(s$,6,1))
sb=ASC(MID$(s$,7,1))
xs=STR2BIN(int8,MID$(s$,8,1))
ys=STR2BIN(int8,MID$(s$,9,1))
ss=ss+STR2BIN(int8,MID$(s$,10,1))
LOOP UNTIL x>=0 AND x<MM.HRES AND y>=0 AND y< MM.VRES 'trap missreads
END SUB

SUB I2Cx p%, I2Ccmd$
SELECT CASE p%
CASE 1
EXECUTE "I2C "+I2Ccmd$
CASE 2
EXECUTE "I2C2 "+I2Ccmd$
CASE 3
EXECUTE "I2C3 "+I2Ccmd$
END SELECT
END SUB

Jim

VK7JH
MMedit

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