Jumpers
2.5
Jumpers
HDK board has one jumper to select crystal or oscillator for MCU.
Table 2-10. Jumpers
Switch
Position 1 - 2
Position 2 - 3
JP1
Oscillator Y3
Crystal Y2
2.6
S3, Power-On Reset Switch
RM42 MCU has two resets: Warm Reset (nRST) and Power-On Reset (nPORRST). Switch S3 is a
momentary switch that asserts power on reset to the RM42L432 device. The nPORRST condition is
intended to reset all logic on the device including the test and emulation circuitry.
2.7
S2, System Reset Switch
Switch S2 is used to assert a warm reset to reset the RM42L432 device. Warm reset does not reset any
test or emulation logic. The reset signal from window watchdog will also assert a warm reset to MCU. The
System Reset can be invoked by pushing nRST button, or by RESET signals from XDS100 CPLD, ARM
JTAG SREST, and CTI JTAG SREST.
2.8
S4, Pushbutton for Clock Failure Test
Switch S4 is a momentary switch that will short the OSCIN pin of the crystal to ground through a current
limiting resistor. Pushing this button simulates a crystal failure and causes a CLKDET hardware fault on
MCU. By default this detection will trigger the Error Signaling Module (ESM) to drive the nERROR pin. On
RM42 HDK, the red LED will then light. The error can be cleared by the nPORRST (S3), cycling the power
to the MCU or via safety software executed on the MCU.
17
SPNU567 – September 2012
Physical Description
Copyright © 2012, Texas Instruments Incorporated
