29 880
modifications
Modifications
Sauter à la navigation
Sauter à la recherche
Ligne 62 :
Ligne 62 : + + + + + + + + + + + + + + + + + + + + +
Pololu-Romi-32U4-Carte-Alimentation (voir la source)
Version du 15 juin 2019 à 21:41
, 15 juin 2019 à 21:41→Logic power selection
The 5 V output of the selection circuit is used to supply the control board’s ATmega32U4 microcontroller, logic power for the DRV8838 motor drivers, and the encoders; it also optionally powers an attached Raspberry Pi.
The 5 V output of the selection circuit is used to supply the control board’s ATmega32U4 microcontroller, logic power for the DRV8838 motor drivers, and the encoders; it also optionally powers an attached Raspberry Pi.
== Raspberry Pi power ==
By default, the control board will provide power from its 5V line to an attached Raspberry Pi. In this situation, we recommend switching on the power circuit so that the Raspberry Pi receives power from the batteries through the control board’s on-board switching regulator. Alternatively, you can use a USB wall power adapter to supply power through the control board’s USB connector, although we have sometimes observed AVR brown-out resets occurring when a board powers the Raspberry Pi this way. A typical computer USB port might not be able to supply enough current to properly power the Romi 23U4 Control Board and an attached Raspberry Pi.
Power provided to the Raspberry Pi can be switched off by driving the Raspberry Pi shutdown pin, '''RPISHDN''', to 5 V.
An ideal diode circuit on the control board makes it safe to have a different power supply connected to the Raspberry Pi (for example, through the Raspberry Pi’s USB Micro-B receptacle) while the control board is connected and powered. (In other words, it is safe to have any combination of control board USB power, battery power, and Raspberry Pi USB power connected to the system.) The '''RPI5V''' pin provides direct access to the Raspberry Pi’s 5 V line, which will typically come from the higher of the two power sources. The 3.3 V output of the Raspberry Pi is also made available on the '''RPI3V3''' pin.
Note that the diode circuit prevents power from being shared in the reverse direction: the Raspberry Pi cannot supply 5 V logic power to the control board through the 40-pin connector.
== Distribution d'alimentation ==
* '''VBAT''' is connected to the battery contact labeled '''BAT1+''' and provides a direct connection to the battery supply.
* '''VRP''' provides access to the battery voltage after reverse-voltage protection.
* '''VSW''' is the battery voltage after reverse protection and the power switch circuit.
* '''VREG''' is the output of the on-board 5 V regulator.
* '''5V''' is the output of the TPS2113A power multiplexer circuit which is connected to VREG by default, but switches to 5 V USB power if VREG is too low.
* '''3V3''' is the output of the 3.3 V LDO regulator.
See Section 3.6 for a diagram of the board’s power distribution buses and access points.
{{Pololu-Romi-32U4-TRAILER}}
{{Pololu-Romi-32U4-TRAILER}}