![](templates/subSilver/images/CCSLogo.jpg) |
![CCS C Software and Maintenance Offers](templates/subSilver/images/forumAd6.jpg) |
View previous topic :: View next topic |
Author |
Message |
codewrecker2
Joined: 23 Dec 2005 Posts: 23
|
SPI problem with max6950 |
Posted: Fri Jul 20, 2007 4:26 am |
|
|
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
|
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
|
Shouldnt that be 94h instead of 14h in both setup and write modules?
Just for the record,my PCM ver. is 3.237 |
|
![](templates/subSilver/images/spacer.gif) |
Ttelmah Guest
|
|
Posted: Fri Jul 20, 2007 6:30 am |
|
|
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 |
|
![](templates/subSilver/images/spacer.gif) |
codewrecker2
Joined: 23 Dec 2005 Posts: 23
|
|
Posted: Fri Jul 20, 2007 12:17 pm |
|
|
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. |
|
![](templates/subSilver/images/spacer.gif) |
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|