Add a warning about duplicate USB pullup for STM32F4 boards

This is suboptimal hardware design, which might need some special care
on the software side. This noticed in the Arduino_Core_STM32, see
stm32duino/Arduino_Core_STM32#1029

For these boards, a schematic is available to confirm the resistor:
 - STM32F407VET6-STM32-F4VE-V2.0
 - STM32F407ZGT6-VCC-GND-Large
 - STM32F407VET6-VCC-GND-Small

These boards have not schematic, but there is a 1.5kΩ resistor clearly
visible in the USB data path that is almost certainly a fixed pullup:
 - STM32F407VET6-Euse-M4-DEMO-Medium
 - STM32F407VGT6-SR-Board

These boards have a pullup, but it is switched by a transistor. Since
there are also internal pullups, a warning is still in order, but using
slightly different wording:
 - STM32F401RCT6-STM32F-Core-Board
 - STM32F407ZGT6-STM32F-Core-Board

All other F4 boards have no such resistor in the schematic or visible in
the images. Other series might also have this problem, but were not
checked.

Author: matthijskooijman

_data/boards/STM32F401RCT6-STM32F-Core-Board.json

@@ -38,7 +38,8 @@
         "mounting": "None"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional switchable pull-up resistor on D+ (R11, controlled by PD2), which is disabled by default. This resistor is not needed and violates the USB specification when used at the same time as the internal pull-up resistors. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407VET6-Euse-M4-DEMO-Medium.json

@@ -41,7 +41,8 @@
         "mounting": "4x mounting hole (M2)"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional pull-up resistor on D+. This resistor is not needed and violates the USB specification when the internal pull-up resistors are also used. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407VET6-STM32-F4VE-V2.0.json

@@ -38,7 +38,8 @@
         "mounting": "4x mounting hole (M3)"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional pull-up resistor on D+ (R21). This resistor is not needed and violates the USB specification when the internal pull-up resistors are also used. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407VET6-VCC-GND-Small.json

@@ -38,7 +38,8 @@
         "mounting": "None"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional pull-up resistor on D+ (R21). This resistors is not needed and violates the USB specification when the internal pull-up resistors are also used. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407VGT6-SR-Board.json

@@ -35,7 +35,8 @@
         "mounting": "None"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional pull-up resistor on D+ (R8). This resistor is not needed and violates the USB specification when the internal pull-up resistors are also used. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407ZGT6-STM32F-Core-Board.json

@@ -38,7 +38,8 @@
         "mounting": "None"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional switchable pull-up resistor on D+ (R14, controlled by PA8), which is disabled by default. This resistor is not needed and violates the USB specification when used at the same time as the internal pull-up resistors. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {

_data/boards/STM32F407ZGT6-VCC-GND-Large.json

@@ -38,7 +38,8 @@
         "mounting": "None"
     },
     "remarks": [
-        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." }
+        { "type": "warning", "content": "The +5V pins on this board are directly connected to the +5V pin of the USB connector. There is no protection in place. Do not power this board through USB and an external power supply at the same time." },
+        { "type": "warning", "content": "The microcontroller on this board features internal pull-up resistors for the USB data lines. However, this board has an additional pull-up resistor on D+ (R8). This resistor is not needed and violates the USB specification when the internal pull-up resistors are also used. This may cause errors while using USB on this board." }
     ],
     "resources": [
         {