STMicroelectronics 32L4R9IDISCOVERY, User Manual

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UM2271 Hardware layout and configuration
77
10.6.2 MCU power supply options
32L4R9IDISCOVERY offers possibility to supply the MCU under 1.8 V or 3.3 V. The JP7
jumper must be placed on +3V3 to supply the MCU with 3.3 V, connecting pins 1 and 2. The
jumper can be placed on +1V8 of JP7 to supply the MCU with 1.8 V, connecting
pins 2 and 3 (see
Table 7 ).
Functions listed below are not compatible with the +1V8 setting of JP7:
•
OCTOSPI
• PSRAM
•
ARDUINO Uno Revision 3
• CAMERA
•
microSD card
• ADC measurements (except if JP3 is set at +3V3, or except if VREF+ configuration is
changed)
•
USB OTG FS (except if JP3 is set at +3V3)
10.6.3 Supplying 32L4R9IDISCOVERY through ST-LINK/V2-1 USB
To power the board through ST-LINK/V2-1, the USB host (a PC) must be connected with the
32L4R9IDISCOVERY standard Micro-B USB receptacle, via a USB cable. This event starts
the USB enumeration procedure. In its initial phase, the current supply capability of the USB
host port is limited to 100 mA. It is enough because only ST-LINK/V2-1 part of
32L4R9IDISCOVERY draws power at that time. If the solder bridge SB36 is open (default
setting), the U11 ST890 power switch is set to Off position, which isolates the remainder of
the board from the power source. In the next phase of the enumeration procedure, the host
PC informs the ST-LINK/V2-1 facility of its capability to supply up to 500 mA current. If the
answer is positive, the ST-LINK/V2-1 sets the U11 ST890 switch to On position to supply
power to the remainder of the board. If the PC USB port is not capable of supplying up to
500 mA, another power source must be used like VIN pin of connector CN16.
Table 6. JP5: ARD 5 V input/output voltage selection setting
Jumper Setting Description
JP5
Default setting.
32L4R9IDISCOVERY supplies 5 V to Arduino connector CN16.
32L4R9IDISCOVERY is supplied by 5 V from Arduino connector
CN16.
SW1 must be placed in OFF position.
Table 7. JP7: VDD setting
Jumper Setting Description
JP7
Default setting.
VDD is powered from +3V3 regulator.
VDD is powered from +1V8 regulator.