Information

The EzPort provides a simple interface to connect an external device to the flash memory
on board a 32 bit microcontroller. The interface itself is compatible with the SPI
interface, with the EzPort operating as a slave, running in either of the two following
modes. The data is transmitted with the most significant bit first.
• CPOL = 0, CPHA = 0
• CPOL = 1, CPHA = 1
Commands are issued by the external device to erase, program, or read the contents of the
flash memory. The serial data out from the EzPort is tri-stated unless data is being driven.
This allows the signal to be shared among several different EzPort (or compatible)
devices in parallel, as long as they have different chip-selects.
29.2 External signal description
The following table contains a list of EzPort external signals, and the following sections
explain the signals in detail.
Table 29-1. EzPort external signal description
Name Description I/O
EZP_CK EzPort Clock Input
EZP_CS EzPort Chip Select Input
EZP_D EzPort Serial Data In Input
EZP_Q EzPort Serial Data Out Output
29.2.1 EzPort Clock (EZP_CK)
EZP_CK is the serial clock for data transfers. The serial data in (EZP_D) and chip select
(EZP_CS) are registered on the rising edge of EZP_CK, while serial data out (EZP_Q) is
driven on the falling edge of EZP_CK.
The maximum frequency of the EzPort clock is half the system clock frequency for all
commands except when executing the Read Data or Read FlexRAM commands. When
executing these commands, the EzPort clock has a maximum frequency of one-eighth the
system clock frequency.
Chapter 29 EzPort
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 561