NXP Semiconductors S32G2 User manual

S32G2 Vehicle Network Processor - Clock
Configuration Guide
by: NXP Semiconductors
1.Introduction
NXP’s S32G2 is a family of high-performance
vehicle network processors that combines Controller
Area Network (CAN), Local Interconnect Network
(LIN), and FlexRay networking with high-data-rate
Ethernet networking. It also combines a functional
safe-core infrastructure with MPU cores and includes
high-level security features.
S32G2 supports multiple clock sources for clock
generation:
•Fast Internal RC Oscillator (FIRC) (48 MHz)
•Slow Internal RC Oscillator (SIRC) (32 KHz)
•Fast External Crystal Oscillator (FXOSC) (20
–40 MHz)
•Phase-Locked Loops (PLLs)
•Digital Frequency Synthesizer (DFS) modules
This application note is intended to provide the user
values for commonly used PLL/DFS configurations.
This document is accompanied with an attached clock
configurator - S32G2_Clock_Configurator.xlsx. The
calculator simplifies the clock configuration process
by helping user find the recommended and validated
values of PLL parameters (MFI, MFN and DIV), DFS
parameters (MFI and MFN), MC_CGM parameters
NXP Semiconductors
Document Number: AN13354
Application Notes
Rev. 1
,
11/2021
Contents
1. Introduction....................................................................1
2. PLL................................................................................2
3. DFS................................................................................4
4. Clock calculator design...................................................6
4.1 Options tab........................................................... 6
4.2 Configuration tab.................................................. 7
4.3 Spread spectrum tab.............................................. 8
4.4 Clock calculator key considerations....................... 9
5. Spread Spectrum........................................................... 10
5.1 Frequency modulation programming................... 10
5.2 Spread Spectrum Considerations......................... 11
5.3 Example code..................................................... 12
6Clock Configuration using S32DS Clocks Tool.............. 13
7References.................................................................... 15

PLL
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
2 NXP Semiconductors
(SELCTL and DIV) to achieve the target clock frequency along with the calculation of STEPNO and
STEPSIZE for programming modulation depth and modulation frequency.
This document complements the S32G2 Reference Manual1and S32G2 Data Sheet2. Readers are
advised to read through “Clocking” chapter from S32G2 Reference Manual1before further diving into
this document.
The following table shows the abbreviations used throughout the document.
Table1. Acronyms and abbreviations
Abbreviation
Explanation
DFS
Digital Frequency Synthesizer
EMI
Electromagnetic Interference
FIRC
Fast Internal RC Oscillator
fMOD
Modulation Frequency
fPLL_VCO
PLL VCO frequency with SSCG enabled
fREF
PLL Reference Clock
FXOSC
Fast External Crystal Oscillator
LDF
Loop Division Factor
MD
Modulation Depth
PLL
Phase Locked Loop
SSCG
Spread Spectrum Clock Generation
2.PLL
The document provides the coherent values for the following PLLs:
1. CORE_PLL
2. PERIPH_PLL
3. ACCEL_PLL
4. DDR_PLL

PLL
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
NXP Semiconductors 3
Figure 1. PLL block diagram
The user need to configure the value for below parameters to achieve the target frequencies for
PLL_VCO and PLL_PHIn.
1. Reference clock : Clock sources for the PLLs can either be the 20 –40 MHz FXOSC or 48 MHz
FIRC. During boot, FIRC_CLK is used as the default PLL reference clock. After boot, the PLL
reference must be changed to FXOSC_CLK. Ensure that PLLCLKMUX[REFCLKSEL] is
selected accordingly.
RDIV : PLL input reference clock frequency after pre-divider should be between 20 –40 MHz,
therefore the valid values for RDIV are shown in the following table.
Table2. RDIV values
Frequency
RDIV
FXOSC –20 MHz
1
FXOSC –24 MHz
1
FXOSC –40 MHz
1 or 2
FIRC –48 MHz
2

DFS
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
4 NXP Semiconductors
NOTE
For a crystal of 40 MHz, NXP recommends using RDIV = 1 for better
jitter performance.
2. MFI : Integer part of LDF
3. MFN : Numerator of fractional LDF
4. DIV : Division value
5. STEPSIZE : Step size for modulation depth and frequency in frequency modulation mode
6. STEPNO : Number of steps to achieve modulation depth in frequency modulation mode.
3.DFS
The document provides the coherent values for following DFS:
1. CORE_DFS
2. PERIPH_DFS

DFS
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
NXP Semiconductors 5
Figure 2. DFS block diagram
The user needs to configure the value for the below parameters to achieve the target frequencies for
CORE_DFSn and PERIPH_DFSn.
1. PLL_VCO : Respective PLL_VCO frequency serves an input clock source to the DFS block.
2. MFI : Integer part of LDF.
3. MFN : Numerator of fractional LDF

Clock calculator design
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
6 NXP Semiconductors
4.Clock calculator design
The S32G2 clock configurator is in the form of an interactive Microsoft Excel spreadsheet organized in
multiple tabs as explained in below sub-sections.
4.1 Options tab
The options tab provides an interface to select the following:
1. FXOSC frequency
Figure 3. Selecting FXOSC frequency
2. RDIV –RDIV is selected individually for each PLL : CORE_PLL, PERIPH_PLL,
ACCEL_PLL, DDR_PLL.
Figure 4. Selecting RDIV value
RDIV must be selected to ensure that the input frequency of each PLL is between 20 –40 MHz.
3. Option to enable/disable SSCG for CORE_PLL, ACCEL_PLL and DDR_PLL.
Figure 5. Enabling/Disabling SSCG
4. Clock Source –Select the clock source.
Figure 6. Selecting the clock source

Clock calculator design
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
NXP Semiconductors 7
5. Target Frequency –Select the target frequency.
Figure 7. Selecting the clock frequency
In case of CORE_PLL, DDR_PLL, ACCEL_PLL, the sheet lists a set of frequencies to support
the SSCG disabled case and the corresponding set of frequencies with 1.5% modulation depth
for SSCG enabled case.
As an example for A53_CORE_CLK : In case SSCG is disabled, the calculator provides 500
MHz, 800 MHz and 1000 MHz frequency options.
Figure 8. FA53_CORE_CLK with SSCG disabled
And when SSCG modulation is enabled, the calculator provides frequency options with 1.5%
modulation depth - 496.3 MHz, 794 MHz, 992.5 MHz.
Figure 9. FA53_CORE_CLK with SSCG enabled
4.2 Configuration tab
After selecting the parameters in the options tab, the calculator provides the value for PLL parameters
(MFI, MFN, DIV), DFS parameters (MFI, MFN) and MC_CGM parameters (SELCTL, DIV) in the
configurations tab on the basis of the selection in the options tab.

Clock calculator design
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
8 NXP Semiconductors
As an example if the user selects the clock source for CAN_PE_CLK as PLL and 40 MHz as the target
frequency with RDIV and FXOSC value as 1 and 40 MHz respectively, the configuration tab provides
the values for clocking parameters as shown in the following image.
Figure 10. Configurations as per the selected parameters
4.3 Spread spectrum tab
With the help of this tab user can calculate values for STEPNO and STEPSIZE to program the
modulation depth and the modulation frequency.
The calculator takes the below input parameters:
1. VCO frequency with SSCG disabled
2. Reference frequency
3. RDIV
4. Modulation frequency
5. Modulation depth
User needs to enter the value for VCO frequency with SSCG disabled, modulation frequency and
modulation depth and select reference frequency and RDIV from the drop down list.
An example to calculate STEPNO and STEPSIZE for the CORE_PLL is shown below.
Figure 11. Spread spectrum tab

Clock calculator design
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
NXP Semiconductors 9
4.4 Clock calculator key considerations
1. RDIV –User must ensure that RDIV value remains in range when selecting or changing a
FXOSC frequency and manually update the RDIV value such that an invalid option is not
selected for the FXOSC frequency.
As an example, if the initial values for FXOSC and RDIV are selected as 40 MHz and 2
respectively and the user update the FXOSC frequency to 20 MHz, the RDIV block turns pink to
indicate the RDIV holds an invalid option for the selected FXOSC frequency. Therefore, the user
must correct the RDIV value in case the FXOSC frequency is updated.
Figure 12. Invalid RDIV error
Same precaution needs to be taken care while updating the FXOSC frequency in Spread
Spectrum tab.
2. Target frequency –As explained above, caution needs to be exercised while enabling or
disabling the SSCG mode. User should manually update the frequency when SSCG mode is
updated.
As an example, if Spread Spectrum is enabled for DDR_PLL and DDR_CLK is selected as 794
MHz and the user disables the spread spectrum, the FDDR_CLK block turns pink to indicate user to
update the FDDR_CLK from the list of frequencies in SSCG disabled mode.
Figure 13. Frequency update error
3. In the Spread Spectrum tab, user must ensure that the specified value for VCO frequency with
SSCG disabled, Modulation frequency and Modulation depth are within range as specified in
section Spread Spectrum Considerations.
Any invalid value selection leads to the specified parameter block turning pink. User must adjust
the value of specified parameter to be within range.

Spread spectrum
S32G2 Vehicle Network Processor - Clock Configuration Guide, Rev. 1, 11/2021
10 NXP Semiconductors
Figure 14. VCO frequency out of specified range
5. Spread spectrum
Spread Spectrum clocking is a technique used in electronic design to intentionally modulate the ideal
position of the clock edge such that the resulting signal’s spectrum is “spread” around the ideal
frequency of the clock. Spread Spectrum clocking is often used to help meet the regulated EMI
requirements.
This section provides the user instructions on how to enable Spread Spectrum functionality.
For S32G2, Spread Spectrum clock modulation is only available for the Core, Accelerator and DDR
PLLs.
PLL operates in frequency modulation mode when the user sets the following bits as shown in the table
below –
Table 3. Mode to enable spread spectrum
PLLCR[PLLPD]
PLLFD[SDMEN]
PLLFM[SSCGBYP]
PLLFM[SPREADCTL]
0
1
0
0
5.1 Frequency modulation programming
Modulation depth and modulation frequency programming uses step number (PLLFM[STEPNO]) and
step size (PLLFM[STEPSIZE]) which can be calculated by using the below equations:
󰇟󰇠  
    󰇟󰇠
Equation 1