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codewrecker2
Joined: 23 Dec 2005
Posts: 23
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| SPI problem with max6950 |
 Posted: Fri Jul 20, 2007 4:26 am |
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Hello folks,I am driving 5 7-seg displays with max6950 and 16f689 as the master mcu.I use the built in H/W SPI to transfer data.The wierd thing is ,when i try to setup the SPI using CCS library functions,i get the following condition
| Code: |
#define SPI_MODE_0_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
.................... ////////////////////////////////////////////////
.................... ////*Internal Peripherals Enable/Disable*/////
.................... ////////////////////////////////////////////
....................
.................... void Internal_Peripherals_init(void)
.................... {
.................... setup_spi(SPI_MASTER|SPI_MODE_0_0|SPI_CLK_DIV_4);
*
030E: BCF 14.5
030F: BSF 03.5
0310: BCF 07.7
0311: BSF 06.4
0312: BCF 06.6
0313: MOVLW 20
0314: BCF 03.5
0315: MOVWF 14
0316: MOVLW 40
0317: BSF 03.5
[color=red]0318: MOVWF 14[/color]
.................... //disable_interrupts(INT_SSP);
.................... //SET_TRIS_B(0x20); // |0|0|1|0|-|-|-|-| see pin_assignments.txt
.................... //TrisB could be reset by setup_spi.We dont read SPI so TRIS adjusted .
....................
.................... //comparator disabled below,not needed
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Also when i try to write SPI data to port,i get the following:
| Code: |
.................... void my_spi_write(int8 reg_address,int8 reg_value)
.................... {
.................... int8 count,buf[2];
....................
.................... buf[0]=reg_address;
*
02E4: MOVF 55,W
02E5: MOVWF 58
.................... buf[1]=reg_value;
02E6: MOVF 56,W
02E7: MOVWF 59
....................
.................... for(count=0;count<2;count++)
02E8: CLRF 57
02E9: MOVF 57,W
02EA: SUBLW 01
02EB: BTFSS 03.0
02EC: GOTO 2F7
.................... {
.................... spi_write(reg_address);
02ED: MOVF 55,W
02EE: MOVWF 13
02EF: BSF 03.5
[color=red]02F0: BTFSC 14.0[/color]
02F1: GOTO 2F4
02F2: BCF 03.5
02F3: GOTO 2EF
.................... }
02F4: BCF 03.5
02F5: INCF 57,F
02F6: GOTO 2E9
....................
.................... }
02F7: RETLW 00
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Shouldnt that be 94h instead of 14h in both setup and write modules?
Just for the record,my PCM ver. is 3.237 |
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Ttelmah
Guest
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| Posted: Fri Jul 20, 2007 6:30 am |
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No.
There is actually no such possible instruction as 'MOVWF 0x94'. If you look at the instruction description, only _seven bits_ are allowed for the direct address on this instruction.
What does BSF 03.5 do?....
Basically it provides the 'extra' bit - actually sets one bit of two extra, which are added as the high bits to the instruction.
Best Wishes |
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codewrecker2
Joined: 23 Dec 2005
Posts: 23
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| Posted: Fri Jul 20, 2007 12:17 pm |
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Many thanx on that quick reply .I thot "BSF 03.5" was just a bank switch command to access the SFR(or is it?).feels good to know i was wrong.gets my feet back on ground .
Ok,the reason i went to the listing was because the spi_write was looping forever in mplab sim (SSPBUF wasnt clearing o something like that)
Now i read that mplab(mine is ver7.21) sim dont support spi simulation.does that answer my problem.can i be certain it would work in the real world?
Many thanx. |
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