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projects:electronics:panelmeter [2008/07/18 16:34] – photonicsguy | projects:electronics:panelmeter [2014/11/13 10:50] (current) – external edit 127.0.0.1 | ||
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* {{: | * {{: | ||
* {{: | * {{: | ||
+ | * {{: | ||
+ | * {{: | ||
===== 1mA Full scale meter ===== | ===== 1mA Full scale meter ===== | ||
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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, | ||
+ | BCF PORTC, | ||
+ | endm | ||
+ | |||
+ | ;Setup direction | ||
+ | BCF TRISB, | ||
+ | BCF TRISC, | ||
+ | BCF TRISC, | ||
+ | |||
+ | ;Set initial pin states | ||
+ | BSF PORTB, | ||
+ | BCF PORTC, | ||
+ | BCF PORTC, | ||
+ | |||
+ | myloop | ||
+ | movlw 0xF0 | ||
+ | movwf DAC, | ||
+ | movlw 0x00 | ||
+ | movwf DAC+1, | ||
+ | CALL SPIclkout | ||
+ | CALL Delay | ||
+ | goto myloop | ||
+ | |||
+ | ; ================= | ||
+ | ; === Functions === | ||
+ | ; ================= | ||
+ | SPIclkout | ||
+ | BCF PORTB, | ||
+ | BCF PORTC, | ||
+ | SPIclk | ||
+ | SPIclk | ||
+ | SPIclk | ||
+ | BSF PORTC, | ||
+ | SPIclk | ||
+ | MOVLW 0x08 | ||
+ | MOVWF Temp, | ||
+ | SPIloop | ||
+ | BTFSS DAC, | ||
+ | BCF PORTC, | ||
+ | BTFSC DAC, | ||
+ | BSF PORTC, | ||
+ | SPIclk | ||
+ | RLNCF DAC, | ||
+ | DECFSZ Temp, | ||
+ | goto SPIloop | ||
+ | |||
+ | MOVLW 0x04 | ||
+ | SPIloop2 | ||
+ | BTFSS DAC+1, | ||
+ | BCF PORTC, | ||
+ | BTFSC DAC+1, | ||
+ | BSF PORTC, | ||
+ | SPIclk | ||
+ | RLNCF DAC+1, | ||
+ | DECFSZ Temp, | ||
+ | goto SPIloop2 | ||
+ | |||
+ | RLNCF DAC+1, | ||
+ | RLNCF DAC+1, | ||
+ | RLNCF DAC+1, | ||
+ | RLNCF DAC+1, | ||
+ | BSF PORTB, | ||
+ | return | ||
+ | </ |