TWR-K65F180M User's Guide
,
Rev. 0
,
05/2015
Freescale Semiconductor, Inc.
11
3.15 Ethernet and 1588
The K65FN2M0VMI18 features a 10/100 Mbps Ethernet MAC with MII and RMII interfaces. The
TWR-K65F180M routes RMII interface signals from the K65 MCU to the primary elevator connector
which enables a connection to an external Ethernet PHY that can be found on some Tower peripheral
modules.
The reason that only RMII instead of MII interface signals are routed out is because there is
multiplexing of the Flexbus function on some of the MII signals. Routing only the RMII signals enables
Ethernet and Flexbus functions to work at the same time.
When the K65 Ethernet MAC is operating in RMII mode, synchronization of the MCU clock and the
50 MHz RMII transfer clock is important. The MCU input clock must remain in phase with the 50 MHz
clock supplied to the external PHY. According to the K65 reference manual, the RMII clock can be
selected between EXTAL and ENET_1588_CLKIN (PTE26) and because the system oscillator is
already connected with 16 MHz to allow HS USB PHY to function, the RMII clock is coming from
PTE26 and this signal is connected to CLKIN0 (B24) of the primary elevator.
4 Jumper table
There are several jumpers provided for isolation, configuration, and feature selection. See the following
table for details.
Table 4.
TWR-K65F180M jumper table
Jumper
Option
Setting
Description
Default
setting
J1
MCU power connection
On
Connect V_SUPPLY and V_BRD with MCU_PWR
On
Off
Disconnect V_SUPPLY and V_BRD with MCU_PWR
J2
VDD and VDDA connection
On
Connect VDD and VDDA
On
Off
Disconnect VDD and VDDA
J3
VBAT power selection
1-2
Connect VBAT to on-board 3.3 V supply from V_SUPPLY
1-2
2-3
Connect VBAT to the higher voltage between on-board 3.3 V supply
or coin cell supply
J4
Tamper signal header
2-3
Tamper signal header
2-3
J6
RESET button connection
1-2
When powering the OPENSDA MCU, bootloader mode can be
selected
1-2
2-3
When OPENSDA MCU is not powered, RESET button can be used
J8
5V power connection
On
Connect P5V_TRG_USB to input of on-board 3.3 V regulator
On
Off
Disconnect P5V_TRG_USB to on-board 3.3 V regulator
J9
Board power selection
1-2
V_SUPPLY comes from OPENSDA MCU (K20) USB regulator
5-6
3-4
V_SUPPLY comes from on-board 1.8 V regulator
5-6
V_SUPPLY comes from on-board 3.3 V regulator
7-8
V_SUPPLY comes from K65 USB regulator
J10
TWRPI power selection
On
Connect V_BRD to TWRPI connector power
On
OFF
Disconnect V_BRD to TWRPI connector power
