NXP Semiconductors K32 L2A Series, Reference Manual, Page: 294 / 1379

14.4 Peripherals Supported
This section describes the peripherals supported by the Kinetis ROM Bootloader. To use
an interface for bootloader communications, the peripheral must be enabled in the BCA,
as shown in
Table 14-3 . If the BCA is invalid (such as all 0xFF bytes), then all
peripherals will be enabled by default.
14.4.1 LPI2C Peripheral
The Kinetis Bootloader in ROM supports loading data into flash via the LPI2C
peripheral, where the LPI2C peripheral serves as the LPI2C slave. A 7-bit slave address
is used during the transfer.
Customizing an LPI2C slave address is also supported. This feature is enabled if the
Bootloader Configuration Area (BCA) (shown in
Table 14-3 ) is enabled (tag field is
filled with ‘kcfg’) and the i2cSlaveAddress field is filled with a value other than 0xFF.
0x10 is used as the default LPI2C slave address.
The maximum supported LPI2C baud rate depends on corresponding clock configuration
field in the BCA. Typical supported baud rate is 400 kbps with factory settings. Actual
supported baud rate may be lower or higher than 400 kbps, depending on the actual value
of the clockFlags and the clockDivider fields.
Because the LPI2C peripheral serves as an LPI2C slave device, each transfer should be
started by the host, and each outgoing packet should be fetched by the host.
• An incoming packet is sent by the host with a selected LPI2C slave address and the
direction bit is set as write.
• An outgoing packet is read by the host with a selected LPI2C slave address and the
direction bit is set as read.
• 0x00 will be sent as the response to host if the target is busy with processing or
preparing data.
The following flow charts demonstrate the communication flow of how the host reads
ping packet, ACK and response from the target.
Peripherals Supported
K32 L2A Reference Manual, Rev. 2, 01/2020
294 NXP Semiconductors