AN2511 Datasheet, PDF (23/43 Pages) STMicroelectronics – This application note describes

AN2511
PMBus commands and source code
PCOR = CONTROL ;
PCDR = CONTROL ;
/*----------------------- Alert Interrupt configuration ---------------------
----------*/
EnableInterrupts;
/* Resets interrupt mask */
MISCR1 = 0x10 ;
/* EI0 on falling edge low level for Alert interrupt */
/*---------------------PMBus communication configuration-------------------*/
while (1)
{
/* I2C configuration: ST7 I2C address 0x30, communication speed 100kHz */
PMBus_Init (SMBs_MISC, SLAVEADD, 0x40, 0x23);
/* Checking if an alert signal is received from slave */
if (SMBus_Mode & SMB_ARA)
{
/* ST7 I2C sends the alert response address to check which slave
alerted */
PMBus_Err = SMBm_ReceiveByte (ALERTRESPONSEADD, Data_Buff);
/* Alerted slave address will be used for any further communication */
PMBus_SlaveAdd = *Data_Buff ;
SMBus_Mode &= (unsigned char) ~SMB_ARA ;
}
Command_Code = 0x01; /* User should enter the PMBus command code here */
PMBus_CommandWrite (Command_Code); /* Writes data from Data_Buff */
Command_Code = 0x02; /* User should enter the PMBus command code here */
/* Read data and store it in Data_Buff */
PMBus_CommandRead (Command_Code);
if (SMB_Err_Status)
{
errors */
SMB_Err_Status = I2CSR2 ;
SMB_Err_Status = 0 ;
}
}
}
/* I2C status register read to clear any
/* End of while (1) */
/* End of main */
3.4
Limitations
1. The SMBus driver used in this application note is tested only for write word, read word
and write block protocols with PEC disabled.
2. The SMBus driver doesn't meet the clock low extending feature of SMBus v1.1 due to
the limitation of the I²C peripheral.
3. In case of PEC, when slave is acting as receiver, the ACK bit is not disabled if the PEC
received from master transmitter is different from slave. It is stored in the user address
as the last byte. It is the responsibility of the user to check the master PEC with the
slave PEC to decide on data validity.
Doc ID 13286 Rev 2
23/43