Here are the register settings to disable interrupts and to set up for as much automatic acknowledgement and PEC calculation as possible:
- PMBCTRL1 – All zeroes – this is the default, so no write is necessary
- PMBCTRL2 – Several bits need to be set
- RX_BYTE_ACK_CNT = 3 – this means up to 3 bytes will be auto acknowledged – it is the default state of these bits after reset
- PEC_ENA = 1 – this enables the automatic PEC calculation logic – this is not the default state
- SLAVE_MASK = 0x7F - This makes the interface auto acknowledge only one address – this is the default state.
- SLAVE_ADDR = desired slave address – this defaults to 0x7c
- The other bits in PMBCTRL2 should be left in the default zero state for this mode
- PMBCTRL3 – set SLAVE_EN, clear all other bits – this is the default state
- In slave mode, even if 400 kHz is desired, there’s no need to set the FAST_MODE bit.
- FAST_MODE only affects the timing of the BUS_FREE bit and, of course, the output clock rate, both of which are only used in master mode. It has no effect on any slave mode timings.
- PMBINTM – set all bits to mask off all PMBus interrupts – this is the default state