Ten problem został po raz pierwszy pokazany w post #58.
Zasilanie modułu discovery przez CN14, czyli złącze USB ST-Link jest inaczej traktowane niż w przypadku 4 innych metod. Wyjaśnienie znajdziesz w manualu ST UM1907 rozdział 6.2 Power Supply.
"The STM32F746G-DISCO discovery board can be powered from the ST-LINK USB connector CN14 (5V link), but only the ST-LINK circuit has the power before USB enumeration, because the host PC only provides 100 mA to the board at that time. During the USB enumeration, the STM32F746G-DISCO board asks for the 500 mA power to the host PC. If the host is able to provide the required power, the enumeration ends by a “SetConfiguration” command and then, the power transistor U8 (ST890) is switched ON, the red LED LD2 is turned ON, thus the STM32F746G-DISCO board can consume no more than 500 mA of current. If the host is not able to provide the requested current, the enumeration fails. Therefore the ST890 (U8) remains OFF and the STM32 part including the extension board will not be powered. As a consequence the red LED LD2 remains turned OFF. In this case it is mandatory to use an external power supply."
i po rysunku dalej jest napisane
"Note:In case the board is powered by a USB charger, there is no USB enumeration, so the led LD2 remains set to OFF permanently and the board is not powered. Only in this specific case, the resistor R109 needs to be soldered, to allow the board to be powered anyway.
The LED LD2 is lit when the STM32F746G-DISCO discovery board is powered by the 5V correctly."
I tu UWAGA na przesunięcie oznaczeń rezystorów na module. Rezystor R109 nie jest wlutowany! Może nieco mylić umieszczony obok niego napis R108 ale to efekt przesunięcia napisów w dół, oznaczony kreską na wysokości diody D6.
Na pytanie - czy przez USB FS i HS to działa ze zwykłego zasilacza od smartfona czy też trzeba jakies zworki przekładać? - odpowiedź brzmi TAK ale po wybraniu odpowiedniego sposobu zasilania na JP1.
Pozdrawiam wszystkich,
Mirek
Zasilanie modułu discovery przez CN14, czyli złącze USB ST-Link jest inaczej traktowane niż w przypadku 4 innych metod. Wyjaśnienie znajdziesz w manualu ST UM1907 rozdział 6.2 Power Supply.
"The STM32F746G-DISCO discovery board can be powered from the ST-LINK USB connector CN14 (5V link), but only the ST-LINK circuit has the power before USB enumeration, because the host PC only provides 100 mA to the board at that time. During the USB enumeration, the STM32F746G-DISCO board asks for the 500 mA power to the host PC. If the host is able to provide the required power, the enumeration ends by a “SetConfiguration” command and then, the power transistor U8 (ST890) is switched ON, the red LED LD2 is turned ON, thus the STM32F746G-DISCO board can consume no more than 500 mA of current. If the host is not able to provide the requested current, the enumeration fails. Therefore the ST890 (U8) remains OFF and the STM32 part including the extension board will not be powered. As a consequence the red LED LD2 remains turned OFF. In this case it is mandatory to use an external power supply."
i po rysunku dalej jest napisane
"Note:In case the board is powered by a USB charger, there is no USB enumeration, so the led LD2 remains set to OFF permanently and the board is not powered. Only in this specific case, the resistor R109 needs to be soldered, to allow the board to be powered anyway.
The LED LD2 is lit when the STM32F746G-DISCO discovery board is powered by the 5V correctly."
I tu UWAGA na przesunięcie oznaczeń rezystorów na module. Rezystor R109 nie jest wlutowany! Może nieco mylić umieszczony obok niego napis R108 ale to efekt przesunięcia napisów w dół, oznaczony kreską na wysokości diody D6.
Na pytanie - czy przez USB FS i HS to działa ze zwykłego zasilacza od smartfona czy też trzeba jakies zworki przekładać? - odpowiedź brzmi TAK ale po wybraniu odpowiedniego sposobu zasilania na JP1.
Pozdrawiam wszystkich,
Mirek