Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 4/01/2024
Public

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5.8.6.5.11. Derivation of I3C/I2C Timing Parameters from Timing Registers

This section describes how the timing parameters are derived from the timing registers in different bus configurations. In the following tables, CCLK_PER represents the core_clk period.

Table 256.  I2C Open Drain Timing Parameters
Parameter Symbol Legacy Mode 400 KHz/FM Legacy Mode 1 MHz/FM+ Units Notes
SCL Frequency fSCL 1/((I2C_FM_LCNT+I2C_FM_HCNT)*CCLK_PER) 1/((I2C_FMP_LCNT+ I2C_FMP_HCNT)*CCLK_PER) MHz
Setup Time for a Repeated START tSU_STA I2C_FM_HCNT*CCLK_PER I2C_FMP_HCNT*CCLK_PER ns
Hold Time for a Repeated START tHD_STA I2C_FM_HCNT*CCLK_PER I2C_FMP_HCNT*CCLK_PER ns
SCL Clock Low Period tLOW I2C_FM_LCNT*CCLK_PER I2C_FMP_LCNT*CCLK_ PER ns
SCL Clock High Period tHIGH I2C_FM_HCNT*CCLK_PER I2C_FMP_HCNT*CCLK_PER ns
Data Setup Time tSU_DAT (I2C_FM_LCNT*CC LK_PER) –tHD_DAT (I2C_FMP_LCNT*CCLK_PER) – tHD_DAT ns Data setup is considered for the write transfer from controller alone point of view. The system delays are not considered.
Data Hold Time

tHD_DAT

(SDA_TX_HOLD)

SDA_TX_HOLD*CCLK_PER SDA_TX_HOLD*CCLK_PER ns Data hold is considered for the write transfer from controller alone point of view. The system delays are not considered.
Setup Time for STOP tSU_STO I2C_FM_HCNT*CCLK_PER I2C_FMP_HCNT*CCLK_PER ns
Bus Free Time between a STOP Condition and a START Condition tBUF BUS_FREE_TIME* CCLK_PER BUS_FREE_TIME*CCLK_PER ns
Pulse width of Spikes that the Spike Filter must Suppress tSPIKE N/A N/A Spike filter is not included in the I3C
Table 257.  I3C Open Drain Timing Parameters
Parameter Symbol I3C Open Drain Mode Units Notes
Low Period of SCL Clock tLOW_OD I3C_OD_LCNT*CCLK_PER ns
High Period of SCL Clock tHIGH I3C_OD_HCNT*CCLK_PER ns
SDA Data Setup Time During Open Drain Mode tSU_OD (I3C_OD_LCNT*CCLK_PER) -tHD_DAT ns

Data setup is considered for the write transfer from controller alone point of view. The system delays are not considered.

Clock After START Condition tCAS BUS_FREE_TIME*CCLK_PER ns
Clock Before STOP Condition tCBP BUS_FREE_TIME*CCLK_PER ns
Current Master to Secondary Master Overlap time during handoff tMMOverlap I3C_OD_LCNT*CCLK_PER ns This parameter is applicable only in secondary master configuration during master ownership handover.
Bus Available Condition tAVAIL BUS_AVAILABLE_TIME*CCLK_PER ns This parameter is used to generate IBI and is not applicable in master mode. It is applicable only in slave mode of operation to generate IBI.
Bus Idle Condition tIDLE BUS_IDLE_TIME*CCLK_PER ns This parameter is used to generate Hot-Join and is not applicable in master mode. It is applicable only in slave mode of operation.
Bus Free Time Between a STOP Condition and a START Condition tBUF_I3C BUS_FREE_TIME*CCLK_PER ns

For pure bus, this should be a duration of at least tCAS.

For mixed bus (that is, at least one legacy I2C is present on the I3C bus), this should be a duration of at least tBUF (see Table 12).

Time Internal Where New Master Not Driving SDA Low

tMMLock BUS_AVAILABLE_TIME*CCLK_PER ns This parameter is applicable only in secondary master configuration during master ownership handover.
Table 258.  I3C Push-Pull Timing Parameters
Parameter Symbol I3C Push-Pull Mode Units Notes
SCL Clock Frequency fSCL 1/((I3C_PP_LCNT+I3C_PP_HCNT)*CCLK_PER) MHz
SCL Clock Low Period tLOW I3C_PP_LCNT*CCLK_PER ns

For HDR-DDR and HDR-TS mode, the I3C_PP_HCNT register is considered for low period. This is because the legacy I2C devices must not see the transitions of the DDR and TSP modes and it must be filtered out with spike filters in I2C.

SCL Clock High Period (Mixed and Pure Bus) tHIGH I3C_PP_HCNT*CCLK_PER ns
Clock in to Data out for Slave tSCO N/A ns This parameter is for slave to drive data with respect to sampling edge of SCL and controller specifically does not have any delay. It is technology dependent. It is not applicable in master mode.
SDA Signal Data Hold in Push-Pull Mode

tHD_PP (SDA_TX_HOLD)

SDA_TX_HOLD*CCLK_PER ns Data hold is considered for the write transfer from controller alone point of view. The system delays are not considered.
SDA Signal Data Setup in Push-Pull Mode tSU_PP (I3C_PP_LCNT*CCLK_PER) – tHD_PP ns
Clock After Repeated START tCASr BUS_FREE_TIME*CCLK_PER ns
Clock Before Repeated START tCBSr BUS_FREE_TIME*CCLK_PER ns
Capacitive Load per Bus Line (SDA/SCL) Cb N/A ns This parameter is system level parameter and not applicable for I3C component.
Note: For the I3C timing parameters in Agilex™ 5 SOCs refer to the HPS I3C Timing Characteristics in the Device Data Sheet.