Texas Instruments ADS1254, Руководство пользователя

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Jumpers
3-3 Operation
3.1.4 JMP5: MCU Disable
Shorting the pins of this jumper has the same effect as plugging the
ADS1254EVM into a DSP DSK: the onboard regulators are shut down, and if
power is still available, the MCU is disabled. Power may still be supplied
through the external power connectors J4 and J5, or through the DSK;
however, power cannot be supplied to the onboard clock generator from the
DSK, since the clock generator is only supplied from the onboard regulators.
If you want to use an external system to control the ADS1254, instead of the
onboard MCU, you must connect this jumper to prevent conflicts with the MCU.
Since this jumper disables the onboard power supply, you must also power the
board externally.
If JMP5 is shorted, and power is available to the MCU, it is active, but it
effectively disconnects itself from the ADS1254 by 3-stating any pins leading
to the 1254. This prevents conflicts with the DSK. The MCU can still
communicate with the host PC in this mode.