Cypress FM4 Series - Notes When High-Speed CR Is Used for the Master Clock

B. List of Notes
1094 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
1. Notes when High-speed CR is Used for the Master Clock
This section explains notes when the high-speed CR is used for the master clock.
The frequency of the high-speed CR varies depending on the temperature and/or the power supply
voltage.
The following table shows notes on each function macro when the high-speed CR is used for the master
clock.
Furthermore, pay attention to notes when the high-speed CR is used as an input clock of the PLL and the
master clock is selected for PLL.
 Notes on Each Macro
Macro
Function/mode
Notes
Internal Bus Clock
HCLK/FCLK/PCLK0/
PCLK1/PCLK2/
TPIUCLK
When the frequency of the high-speed CR is the maximum
value, the setting of the internal operating clock frequency
shall not exceed the upper limit specified in the "data
sheet" for the product that you are using.
Timer
Multi-function Timer
Base Timer
Watch Timer
Dual Timer
Watch Dog Timer
Quadrature
The frequency variation of the high-speed CR should be
considered for the timer count value of each macro.
A/D Converter
Sampling Time
Compare Time
Considering the frequency variation of the high-speed CR,
the sampling time and the compare time of the A/D
converter shall satisfy the specification specified in the
"data sheet" for the product that you are using.
USB
-
As the frequency accuracy does not meet the required
specification, these macros cannot be used when the
high-speed CR is used for the master clock.
Ethernet-MAC
CAN
CAN-FD
I
2
S
Multi-Function
Serial Interface
UART
Even if the frequency of the high-speed CR is the minimum
or the maximum value, the baud rate error should be
considered.
The baud rate error shall not exceed the limit.
CSIO
The frequency variation of the high-speed CR should be
considered for the communication of each macro.
I2C
LIN
As the required frequency accuracy cannot be met, this
function cannot be used as master.
As a slave, the specified baud rate has more error at the
maximum/minimum frequency of high-speed clock. So, if
the error limit of the baud rate is exceeded, this function
cannot be used.
Debug Interface
Serial Wire
As the frequency variation of the high-speed CR, the
SWV(Serial Wire View) may not be used.
External Bus Interface
Clock Output
When the external bus clock output is used, the frequency
variation of the high-speed CR should be considered for
devices to be connected.
High-Speed Quad SPI
-
The frequency variation of the high-speed CR should be
considered for devices to be connected.