Configuring the EVM
Table 3. Control Pin Interfaces for Soft Pin Mode or Register Default Mode (JP18 HWCTRL = LO)
NAME
COMPONENT
DESCRIPTION
(TYPE)
Hardware / Software Control (HW_SW_CTRL) pin
HWCTRL state is sampled on POR and determines the mode of operation.
HWCTRL STATE
OPERATING MODE
Soft Pin Mode or Register Default Mode
LO
GPIO[3:2] pins are also sampled on POR to determine the initial
HWCTRL
(JP Default)
JP18
page setting loaded to registers (from EEPROM or default).
(2-level input)
Hard Pin Mode
GPIO[5:0] pins are also sampled on POR to determine the initial
HI
page setting loaded to registers (from ROM).
See
: Control Pin Interfaces for Hard Pin Mode (JP18
HWCTRL = HI)
Reference Select (REFSEL) pin for PLL1 and PLL2 Input Muxes
RSEL selects the PLL1 and PLL2 reference input when “Pin Select” is configured by the INSEL_PLL1 or
INSEL_PLL2 register bits (R50[1:0] and R50[3:2]).
PLL1 REF INPUT
PLL2 REF INPUT
RSEL STATE
(1)
(INSEL_PLL1=Pin Select)
(INSEL_PLL2=Pin Select)
LO
PRIREF
SECREF
RSEL
JP17
MID
Auto Select
(2)
SECREF
(3-level input)
HI
Auto Select
(2)
Auto Select
(2)
(JP Default)
(1)
RSEL is ignored when INSEL_PLLx bits
≠
01b.
(2)
In Auto Select mode, PRIREF is prioritized over SECREF when a valid signal is detected by the on-
chip reference detector logic. To use the SECREF input in Auto Select mode, the input signal to
PRIREF must be made invalid (disabled or disconnected).
SYNC pin (active low)
GPIO0 can be used to mute the output clocks (when asserted) and trigger output divider
synchronization (when de-asserted) if synchronization is permitted by the SYNC_MUTE,
PLL1_SYNC_EN, and PLL2_SYNC_EN register bits.
GPIO0
GPIO0 STATE
SYNC OPERATION
JP19
(2-level input)
LO
Assert SYNC: Outputs muted, dividers in reset
HI
Normal output operation
(JP Default)
SYNC can also be asserted when switch S4 is pressed.
I2C Slave Address LSB Select pin
GPIO1 is sampled on POR to configure the lower 2 bits of the 7-bit slave address. The upper 5 bits of
the slave address are initialized from EEPROM (SLAVEADR[7:3] = 10101b). By configuring GPIO1, the
composite slave address can be selected as follows:
7-BIT SLAVE ADDRESS
GPIO1
GPIO1 STATE
JP20
(excludes W/R bit)
(3-level input)
LO
1010100b / 0x54
(JP Default)
MID
1010101b / 0x55
HI
1010111b / 0x57
12
LMK03328EVM User’s Guide
SNAU184 – August 2015
Copyright © 2015, Texas Instruments Incorporated