projects:electronics:panelmeter

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projects:electronics:panelmeter [2008/07/27 14:04] – photonicsguyprojects:electronics:panelmeter [2008/07/27 20:06] – photonicsguy
Line 14: Line 14:
 5K Ohm resistor @ 5V = 1mA 5K Ohm resistor @ 5V = 1mA
  
 +==== MCP4821 ====
  
 +^Pin No.^Symbol^Function^
 +|1|Vdd|Supply (2.7 to 5.5V)|
 +|2|CS|Chip Select|
 +|3|SCK|Serial Clock Input|
 +|4|SDI|Serial Data Input|
 +|5|LDAC|Sync input|
 +|6|SHDN|Hardware shutdown|
 +|7|AVss|Analog ground|
 +|8|VoutA|DACa Output|
 +
 +
 +
 +
 +**PIC Assembly Code**
 +<code asm>
 +SPIclk macro
 + BSF PORTC,SCK
 + BCF PORTC,SCK
 +endm
 +
 + ;Setup direction
 + BCF TRISB,RB1 ; RB1 as Output
 + BCF TRISC,SCL ; SDO as Output
 + BCF TRISC,SDA ; SCK as Output
 +
 + ;Set initial pin states
 + BSF PORTB,RB1 ;Chip Select, active low
 + BCF PORTC,SCK
 + BCF PORTC,SDO
 +
 +myloop
 + movlw 0xF0
 + movwf DAC,A
 + movlw 0x00
 + movwf DAC+1,A
 + CALL SPIclkout
 + CALL Delay
 + goto myloop
 +
 +; =================
 +; === Functions ===
 +; =================
 +SPIclkout
 + BCF PORTB,RB1 ; Clear CS (Active low)
 + BCF PORTC,SDO ; 0
 + SPIclk
 + SPIclk
 + SPIclk
 + BSF PORTC,SDO ; 1
 + SPIclk
 + MOVLW 0x08
 + MOVWF Temp,A
 +SPIloop
 + BTFSS DAC,7
 + BCF PORTC,SDO ; 0
 + BTFSC DAC,7
 + BSF PORTC,SDO ; 1
 + SPIclk
 + RLNCF DAC,F,A
 + DECFSZ Temp,F,A
 + goto SPIloop
 +
 + MOVLW 0x04
 +SPIloop2
 + BTFSS DAC+1,7
 + BCF PORTC,SDO ; 0
 + BTFSC DAC+1,7
 + BSF PORTC,SDO ; 1
 + SPIclk
 + RLNCF DAC+1,F,A
 + DECFSZ Temp,F,A
 + goto SPIloop2
 +
 + RLNCF DAC+1,F,A
 + RLNCF DAC+1,F,A
 + RLNCF DAC+1,F,A
 + RLNCF DAC+1,F,A
 +
 + BSF PORTB,RB1 ; Set CS high
 + return
 +</code>
  • projects/electronics/panelmeter.txt
  • Last modified: 2014/11/13 10:50
  • by 127.0.0.1