Servo memory
Herkulex smart servos have a large amount of control registers. These registers are used for storing things like control algorithm parameters (e.g. PID values), configurable options (e.g. servo ID), and sensor readings (e.g. temperature).
To make things even more complicated, there are two types of memory: non-volatile EEPROM memory and volatile RAM memory. Data stored in RAM is lost every time the servo is powered off, data stored in EEPROM is not. On startup, the servo will read data from the EEPROM and store it in RAM. The RAM registers determine the actual behavior of the servo. Refer to the manual (PDF) for a detailed explanation of what each register does. The HerkulexServo library does not encapsulate all functionality of the servos. For advanced functions, you will have to manipulate registries manually.
Reading from registers
Use the readRam() and readRam2() methods to read data from RAM. These
methods return one and two bytes respectively. Most data is stored in a single
byte of memory, though some registries take up more space. Use the readEep()
and readEep2() methods to read data from the EEPROM. These methods work in the
same way.
Important: Notice the difference between the enum classes
HerkulexRamRegister and HerkulexEepRegister? This is necessary because the
RAM and EEPROM use different addresses for the same register.
Reading from RAM:
uint8_t one_byte = my_servo.readRam(HerkulexRamRegister::Temperature);
uint16_t two_byte = my_servo.readRam2(HerkulexRamRegister::CalibratedPosition);
Reading from EEPROM:
uint8_t one_byte = my_servo.readEep(HerkulexEepRegister::ID);
uint16_t two_byte = my_servo.readEep(HerkulexEepRegister::PositionKp);
Writing to registers
Likewise, the writeRam(), writeRam2(), writeEep(), and writeEep2 methods
can be used to write data to a registry.
Tip: Some registers are read-only and cannot be written to. Please refer to the manual to find out more.
Important: Only the RAM registers have an immediate effect on the behavior of the servo. EEPROM settings only take effect once the servo is rebooted.
Writing to RAM:
my_servo.writeRam(HerkulexRamRegister::ID, 10);
my_servo.writeRam2(HerkulexRamRegister::PositionKp, 800);
Writing to EEPROM:
my_servo.writeEep(HerkulexEepRegister::ID, 10);
my_servo.writeEep2(HerkulexEepRegister::MaxPwm, 400);
Reboot
At startup, the servo copies data from the EEPROM into RAM. As mentioned before,
only RAM registers affect the behavior of the servo. You can choose to restart
the servo using the reboot() method.
Request a reboot:
my_servo.reboot();
Factory defaults
To restore the factory defaults, use the rollbackToFactoryDefaults() method.
You can choose to skip the ID register and/or the Baud rate register, saving you
the hassle of removing the servo from the bus to reprogram its ID.
Reset all registers except ID and baud rate:
my_servo.rollbackToFactoryDefaults(true, true);