USB PD sink controller
Abstraction class for Arduino systems
The AP33772 class provides a simple interface to access the AP33772 chip.
The AP33772 is a USB PD sink controller manufacture by Diodes Incorporated.
It is a full featured easy to use all in one solution. It's features:
- built in protocol engine for requesting source capabilites and negotiating power
- built in current and voltage monitor
- programmable over voltage, over current and over temperature protection
- output to external power FET for switching the load
- I2C interface
- LED (fault) Indicator
- Interrupt line
unlike the FUSB302 form ON Semiconductor there is no need to implement
the prtocol stack for power negotiation. For more details on FUSB 302 see
Ryan Ma's PD-Micro or
Kai Clemens Liebich. They did a great job!
Tha AP33772 offers only PD3.0/PPS support with up to 100 W power. The chip is also available as AP33772S wich operates different. While the AP33772 can set APDO with 20 mV and 50 mA increments the AP33772S has only increments of 100 mV and 1 - 5 A in 16 steps = 250 mA but it can operate at up to 28 V and 150 W utilizing USB Power Delivery Specification Revision 3.1 EPR Profiles.
Ther is a demo board
available from MICROE called usb-c-sink-2-click.
this class for Arduino will be left as is because the AP33772 is marked as not reccomended for new design.
the interface is closely related to the register naming in the datasheet. Keep in mind that the device operates with USB PD data objects such as Capabilies Messages, Power Data Objects, and Request Data Objects. These are all 32 bit blocks. See chapter 6.4.1 and 6.4.2 of the USB Power Delivery Specification Revision 3.1 for details. For a detailed description of the operation of the chip see datasheet and EVKit manual at Diodes Inc.
void init(uint8_t int_pin); // set int pin and do initial read
bool test_chip(void); // check if AP33772 is present
bool test_int_pin(void); // check if int request has been set
uint8_t read_status(void); // read status register
uint8_t get_last_status(void); // get last status flags
uint8_t read_interrupt_mask(void); // read interrupt mask register
void set_interrupt_mask(uint8_t int_mask); // write interrupt mask register
void read_source_pdos(void); // read advertised PDOs into buffer
uint8_t get_pdo_cnt(void); // get number of advertised PDOs
uint32_t get_pdo(uint8_t pdo_num); // get specific PDO, #0 ist used for last RDO
void set_rdo(uint32_t RDO); // set RDO -> request pdo
uint32_t get_last_rdo(void); // get last requested data
uint16_t read_voltage_mV(void); // read voltage register and return voltage in mV
uint16_t read_current_mA(void); // read current register and return current in mA
int8_t read_temperature_C(void); // read temperature register and return temperatur in °C
uint16_t get_voltage_measurement_mV(void); // get voltage in mV from temp. storage
uint16_t get_current_measurement_mA(void); // get current in mA from temp. storage
int8_t get_temperature_measurement_C(void); // get current in °C from temp. storage
uint16_t read_overcurrent_threshold_mA(void); // read overcurrent threshold reg and convert to mA
uint8_t read_overtemperature_threshold(void); // read overtemperatur setting for helath monitoring
uint8_t read_derating_temperature_threshold(void); // read derating setting for health monitoring
uint16_t read_temperature_curve(temperature_et temp); // read temperature curve of ntc
void set_overcurrent_threshold_mA(uint16_t mA); // set overcurrent threshold
void set_overtemperature_threshold_C(uint8_t otp); // set overtemperature threshold
void set_derating_temperature_threshold_C(uint8_t drtp); // set derating threshold
void set_temperature_curve(temperature_et temp, uint16_t R); // set temperature curve of ntc
void reset(void);
The init function needs to called with the digital pin used for the interrupt line.
Note: this pin is polled, there is no interrupt handler attached
When done one could try the test_chip function to check if the chip is actually responding
The set_interrupt_mask function could be use to be alerted when any of the desired functions is triggert. These are the options:
DERATING_INT_FLAG
OVERTEMPERATURE_INT_FLAG
OVERCURRENT_INT_FLAG
OVERVOLTAGE_INT_FLAG
NEWPDO_INT_FLAG
SUCCES_INT_FLAG
READY_INT_FLAG
The status_flags_st bit type has to be used when the status is read.
The temperature sensor has four calibration registers R25, R50, R75, R100. They need to be programmed with the restance values in Ohms of the NTC at the corresponding temperatures 25, 50, 75, and 100 °C.
If desired overvoltage, overcurrent overtemperature and derating temperature thresholds can be set.
when the basic configuration is then, status needs to be checked, when the source pdo's have been successflly advertised the number of source capabilites and the profiles can be read.
| NEWPDO (B2) | SUCCESS (B1) | READY (B0) | Description |
|---|---|---|---|
| - | - | 0 | Status is invalid |
| 0 | 0 | 1 | The host MCU had written the RDO register but the negotiation is unsuccessful |
| 0 | 1 | 1 | The host MCU had written the RDO register and the negotiation is successful |
| 1 | 0 | 1 | The PD source advertise PDOs and the negotiation with RDO is unsuccessful |
| 1 | 1 | 1 | The PD source advertise PDOs and the negotiation with RDO is successful |
Create the desired RDO and request ist.
When the negatiation has been succesful, the load switch will be turned on.
during operation the voltage, current and temperature can be monitored.