Attached the relevant code here. Basically, I can read the source capabilities successfully, and my code selects the "optimal" pdo based desired user voltage/current parameters, writing it to the high priority PDO3 profile. I cannot get the renegotiation to this profile until I use the provided register "reset()" function provided in the code. It does work after that. However, I would like to use the function "send_pd_message()" with the parameter PD_SOFT_RESET to force the renegotiation. The writes are successful, but nothing seems to happen afterwards. Thanks for looking into this.
// STUSB4500 i2c address
#define STUSB_ADDR 0x28
// STUSB4500 registers
#define PORT_STATUS 0x0E
#define PRT_STATUS 0x16
#define CMD_CTRL 0x1A
#define RESET_CTRL 0x23
#define WHO_AM_I 0x2F
#define RX_BYTE_CNT 0x30
#define RX_HEADER 0x31
#define RX_DATA_OBJ 0x33
#define TX_HEADER 0x51
#define DPM_SNK_PDO1 0x85
// STUSB4500 masks/constants
#define STUSB4500_ID 0x25
#define STUSB4500B_ID 0x21
#define SW_RESET_ON 0x01
#define SW_RESET_OFF 0x00
#define ATTACH 0x01
#define PRT_MESSAGE_RECEIVED 0x04
#define SRC_CAPABILITIES_MSG 0x01
// Maximum number of source power profiles
#define MAX_SRC_PDOS 10
// PD protocol commands, see USB PD spec Table 6-3
#define PD_CMD 0x26
#define PD_GET_SRC_CAP 0x0007
#define PD_SOFT_RESET 0x000D
#define RESET_DELAY_MS 27
#define PLUG_TIMEOUT_MS 3000
#define RETRIEVE_TIMEOUT_MS 500
static bool send_pd_message(const uint16_t msg) {
return (
i2c_master_write_u16(STUSB_ADDR, TX_HEADER, msg) &&
i2c_master_write_u8(STUSB_ADDR, CMD_CTRL, PD_CMD));
}
static bool is_present(stusb4500_config_t* config) {
uint32_t time = config->get_ms();
uint8_t res;
do {
if (!i2c_master_read_u8(STUSB_ADDR, WHO_AM_I, &res)) return false;
if (config->get_ms() - time > RETRIEVE_TIMEOUT_MS) return false;
} while (res != STUSB4500_ID && res != STUSB4500B_ID);
return true;
}
static bool reset(stusb4500_config_t* config) {
// Enable software reset
if (!i2c_master_write_u8(STUSB_ADDR, RESET_CTRL, SW_RESET_ON)) return false;
// Wait for VBUS to discharge
uint32_t time = config->get_ms();
while ((uint32_t)(config->get_ms() - time) < RESET_DELAY_MS)
;
// Verify reset success
if (!is_present(config)) return false;
// Disable software reset
if (!i2c_master_write_u8(STUSB_ADDR, RESET_CTRL, SW_RESET_OFF)) return false;
return true;
}
// some other functions here
.....
//
bool stusb4500_negotiate(stusb4500_config_t* config, bool on_interrupt) {
// code to read header here
.....
// Read source capabilities
// WARNING: This must happen very soon after the previous code block is
// executed. The source will send an accept message which partially
// overwrites the source capabilities message. Use i2c clock >= 300 kHz
if (!i2c_master_read(
STUSB_ADDR,
RX_DATA_OBJ,
buffer,
HEADER_NUM_DATA_OBJECTS(header) * sizeof(stusb4500_pdo_t)))
return false;
// Find and load the optimal PDO, if any
if (!load_optimal_pdo(config, (stusb4500_pdo_t*)buffer, HEADER_NUM_DATA_OBJECTS(header)))
return false;
// Force a renegotiation
// NOTE: vbus will be momentarily lost
return reset(config);
}
