pflib::Bias Class Reference

The HGC ROC has 4 MAX5825 chips doing the DAC for the bias voltages. More...

#include <Bias.h>

Collaboration diagram for pflib::Bias:

Public Member Functions
	Bias (std::shared_ptr< I2C > bias_i2c, std::shared_ptr< I2C > board_i2c, bool use_cache)
	Wrap I2C objects for communicating with all the DAC chips.
	Bias (const Bias &)=delete
	dont copy construct this class
Bias &	operator= (const Bias &)=delete
	dont copy assign this class
void	initialize ()
	Initialize to standard settings.
double	readTemp ()
	Read the temperature from the temp sensor on the HGCROC board.
std::optional< int >	readSiPM (uint8_t i_sipm)
std::optional< int >	readLED (uint8_t i_led)
void	setSiPM (uint8_t i_sipm, uint16_t code)
void	setLED (uint8_t i_led, uint16_t code)

Static Public Attributes
static const int	N_CHANNELS = 16
static const uint8_t	ADDR_LED_0 = 0x18
	DAC chip addresses taken from HGCROC specs.
static const uint8_t	ADDR_LED_1 = 0x1A
static const uint8_t	ADDR_SIPM_0 = 0x10
static const uint8_t	ADDR_SIPM_1 = 0x12

Private Attributes
std::shared_ptr< I2C >	i2c_bias_
	I2C comms with bias DACs MAX5825.
std::shared_ptr< I2C >	i2c_board_
	I2C comms with HGCROC board periferials.
std::vector< MAX5825 >	led_
	LED bias chips.
std::vector< MAX5825 >	sipm_
	SiPM bias chips.
bool	use_cache_
	whether to use the software cache of the settings
std::array< std::optional< int >, N_CHANNELS >	sipm_cache_
	cache of sipm settings
std::array< std::optional< int >, N_CHANNELS >	led_cache_
	cache of led settings

Detailed Description

The HGC ROC has 4 MAX5825 chips doing the DAC for the bias voltages.

Two of the chips handle the 16 LED bias voltages and the other two handle the 16 SiPM bias voltages.

Both the LED and SiPM bias voltages are indexed from 0 to 15. The conversion from that index to a chip and DAC index on that chip is done in this class.

The readback of the DAC settings in the MAX5825 seem to require a "repeated start" I2C transaction where the register to be read and the read command are sent before the next I2C stop. Originally pointed out by Lennart at Lund, this "repeated start" transaction cannot be done by the lpGBT, so actual readback of the DAC settings is not supported in fiberfull setups.

Constructor & Destructor Documentation

Bias()

pflib::Bias::Bias	(	std::shared_ptr< I2C >	bias_i2c,
		std::shared_ptr< I2C >	board_i2c,
		bool	use_cache )

Wrap I2C objects for communicating with all the DAC chips.

The bus is 4 + <board-number>, so we set the default to 4 for the case where we only have one board with bus number 0.

Parameters

[in]	bias_i2c	I2C object for interacting with MAX5825 bias DACs
[in]	board_i2c	I2C object for talking with HGCROC board periferials
[in]	use_cache	whether to use the software cache for readback (true) or not (false). This is necessary for readback to function on fiberless setups.

Member Function Documentation

initialize()

void pflib::Bias::initialize

(

)

Initialize to standard settings.

reset all CODEs, DACs, and CRs to zero

Set internal ref on DAC to 4.096 V

Set up the GPIO device MCP23008

Turn on the status LED

Set up the board temperature sensor TMP101

Set up the two onewire-to-I2C devices DS2482

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The documentation for this class was generated from the following files:

• include/pflib/Bias.h
• src/pflib/Bias.cxx