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Firmware for Rev 2 Laser/TEC system

I2C Bus

Four-channel I2C DAC LTC2635 Address as follows by crate slot:

  Slot  I2C   Note
  000   0x20  Slot 0 - default
  001   0x24  Slot 1
  010   0x44  Slot 2
  011   0x60  Slot 3
  100   0xa4  Slot 4
  101   0xc0  Slot 5

I2C bus is common to all uC (and to backplane if R5, R6 on Laser/TEC board installed).

uC Pinout

uC on Laser/TEC is ATMEGA164A

ADC reference should be external (REFS1=REFS0=0)

'Pin Func Name Note
PA0/ADC0 ADC ISENSE Current sense 0.5V = 1A (4.88mA/LSB)
PA1/ADC1 ADC THERM_LASER Laser temperature ADC input (512 @ 25 deg C)
PA2/ADC2 ADC THERM_HOT TEC hot side ADC input (512 at 25 deg C)
PA3/ADC3 ADC FAN_STATUS Pulse if fan running
PA4/ADC4 ADC QTEMP Current source transistor temperature ADC input (512 at 25 deg C)
PA5/ADC5 n.c.
PA6/ADC6 IN TEMP_FAIL Over-temperature (logic 1' if temp outside window) (Note 1)
PA7/ADC7 IN OVER_CURRENT Over-current (logic 1' if over current set by pot)

Note 1 - Window set by R105,R107,R108 (3 per channel). Default values give 2.5V +/- 0.5V. 'Resistors R105 etc must be changed to 30k

'Pin Func Name Note
PB0-PB1 IN CH_ADR0-1 Channel address 0-3
PB2-PB4 IN SL_ADR0-2 Slot address 0-7
PB5-PB7 IN not used programming connector
'Pin Func Name Note
PC0-PC11 I2C I2C SCL/SDA disable except on channel 0?
PC2 OUT LED D1 0' for on, uC status
PC3 OUT LED D5 1' for on, laser on
PC4-PC7 n.c.
'Pin Func Name Note
PD0/RXD0 UART RS-485 Rx RS-485 receive data
PD1/TXD0 UART RS-485 Tx RS-485 transmit data
PD2-PD3 IN FAULT0-1 Fault input for TEC PWM (Note 2)
PD4 OUT PWM- TEC PWM output (Note 3)
PD6 OUT DE RS-485 driver enable
PD7 OUT L_SHDN Laser shutdown. Logic 1' to disable laser

Note 2: PWM condtions: "00"-Overcurrent, "01"-Undervoltage, "10"-Overtemperature, "11"-Normal

Note 3: Assuming TEC is wired with "+ lead to J20 pin 1, PWM+ provides cooling with PWM-='0'. PWM- provides heating with PWM+='0'

Last modified 9 years ago Last modified on Nov 8, 2013, 10:17:53 AM