pcb v1.7 upgrade update

doc/pcb-v1.7-upgrade.md

@@ -25,20 +25,21 @@ Mount:
     U10 FLASH:   IS25LP032D-JNLE-TR SOIC-8 150mil
     U9 WIFI:     ESP32, but not all pins! read below:
 
-Don't connect ESP32 pins leading to SD card
+Don't connect ESP32 pins leading to SD card,
-those are 6 central pins from on the top 10-pin row of
+in the top 10-pin row, connect only 2 pins on left side and 2 pins on right
-ESP32 chip (only 2 pins on left side and 2 pins on right
+and leave 6 central pins unconnected. GND and VCC
-side shuould be connected). Either cut the traces or carefully
+can be connected, but no other SD signal pins.
-solder without touching SD card pins.
+Either cut the traces or carefully solder without 
+touching those pads.
 
 # What is fixed
 
 Shutdown:
 
-on assembled PCB v1.7, D11=1N4148 and R4=15k will
+PCB v1.7 assembled comes with D11=1N4148 and R4=15k, those will
-keep waking the board up after shutdown signal because FT231x internal
+keep waking up the board after shutdown signal because FT231x internal
 regulator will provide enough voltage (cca 2.5V will appear at 3.3V line)
-and that is enough to wakeup the board because voltage
+and that is enough to wake up the board because voltage
 on ENABLE pin at switching regulators will be above its turn on
 threshold of 1.5V.
 
@@ -50,23 +51,22 @@ self-hold switching regulator during normal operation and at controlled
 shutdown signal, it will drop below turn-off threshold, allowing reliable
 shutdown.
 
-Software shutdown is not routed to BGA pads so alternative patch is
+Software shutdown is not routed to BGA pads. It is possible to connect
-to connect any GPIO (we recommend "25-") to SHUTDOWN.
+any GPIO (we recommend "25-") to SHUTDOWN.
 
 I2C:
 
 Too low pull up resistors (470 ohm) are at 5V side of the level converter PCA9306
-and some monitors won't tolerate that. Data traffic at i2c will be
+and some monitors will receive niose with that. If data traffic at i2c is
-errorneously received by some monitors and some serious problem may arrise
+not received 100% error-free, some monitors will get into serious problems.
-if monitor interprets some data garbage as random write command, overwriting
+When monitor interprets some data garbage as random write command and
-its internal settings, then monitor will become useless.
+overwrites its internal settings, such monitor might become premanently
-
+useless. Correct pull up resistors are 4.7k and they should work properly.
-Correct pull up resistors are 4.7k and they work properly.
 
 WIFI:
 
-On PCB v1.7, SD card is connected to ESP32 pins that are widely advertised
+On PCB v1.7 SD card is connected to those ESP32 pins which are widely advertised
-as SD card pins, but the problem is those pins are shared with internal flash
+as SD card pins, but those pins are shared with internal SPI FLASH of ESP32
-chip and ESP32 won't boot from its SPI FLASH if anything is connected there.
+chip it won't boot if anything is connected there.
-SD card should be connected on some other pins, probably HSPI. It has not
+SD card should be connected on some other pins, probably HSPI.
-yet been verified will that work.
+It has not yet been verified will it work, so no patch recommendation yet.