From 9041a4f07a26efb99776a10d0632ff8af589a6b3 Mon Sep 17 00:00:00 2001 From: davor Date: Mon, 25 Dec 2017 14:08:14 +0100 Subject: [PATCH] readme update, separated document for the PCB v1.7 upgrade --- README.md | 13 ++------ doc/pcb-v1.7-upgrade.md | 72 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+), 10 deletions(-) create mode 100644 doc/pcb-v1.7-upgrade.md diff --git a/README.md b/README.md index cca9d67..6db9447 100644 --- a/README.md +++ b/README.md @@ -12,16 +12,9 @@ board release 3 with SDRAM, Successor of [Schematics](/doc/schematics.pdf) is mostly complete. PCB routing is mostly complete too. PCB produced when at version 1.7 and big things work like USB-JTAG, SDRAM, SDCARD, HDMI, FLASH, RTC, I2C -but there are issues: -PCB v1.7 has small issues like SHUTDOWN not connected. -When SHUTDOWN is connnected to 3.3V and released, usually board wakes up again, -cause of that is probably FT231X generating 2.5V from internal regulator -and raising up 3.3V line over FPGA protection diodes. -WiFi won't work if its pins to SDCARD are connected, WiFi disable -jumper won't work if WiFi enable is held high by FPGA. -For some monitors I2C works and for some it doesn't. -Try to increase i2c pullup resistors 470->1.2k. -AUDIO, OLED are currently untested. +but there are issues, luckily most of them are can be fixed by an +[Upgrade for PCB v1.7](/doc/doc/pcb-v1.7-upgrade.md) +AUDIO, OLED and 433.92MHz antenna are currently untested. 3D preview diff --git a/doc/pcb-v1.7-upgrade.md b/doc/pcb-v1.7-upgrade.md new file mode 100644 index 0000000..ce43b3e --- /dev/null +++ b/doc/pcb-v1.7-upgrade.md @@ -0,0 +1,72 @@ +# PCB v1.7 upgrade + +This is the first board produced, most important +parts work which is mirracle in itself, and there +are some mistakes, luckily most of them can be fixed. + +FIX: Replace this parts: + + D11=LED (High efficiency RED recommended) + R4,R25,R26=4.7k + +D11 and R4 are are on the back side on the left, +under the edge of SDRAM chip. + +R25 and R26 are on the back side top, +under the GPDI connector. + +Optionally, as alternative software shutdown, +connected J2 "25-" pin to R13-D15 junction. + +Mount: + + SDCARD: SCHD3A0100 + U11 I2C: PCA9306D SOIC-8 150-mil + 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 +those are 6 central pins from on the top 10-pin row of +ESP32 chip (only 2 pins on left side and 2 pins on right +side shuould be connected). Either cut the traces or carefully +solder without touching SD card pins. + +# What is fixed + +Shutdown: + +on assembled PCB v1.7, D11=1N4148 and R4=15k will +keep waking the board up 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 +on ENABLE pin at switching regulators will be above its turn on +threshold of 1.5V. + +Using higher voltage drop diode (RED, YELLOW or GREEN LED cca 1.7-2V, not +BLUE or WHITE) and adequate resistor, the voltage at ENABLE pin is now about +1.3V, inside of the switching regulator's hysteresis range. ENABLE is +not above turn-on threshold neither below turn-off threshold so it will +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 +to connect 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 +errorneously received by some monitors and some serious problem may arrise +if monitor interprets some data garbage as random write command, overwriting +its internal settings, then monitor will become useless. + +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 +as SD card pins, but the problem is those pins are shared with internal flash +chip and ESP32 won't boot from its SPI FLASH if anything is connected there. +SD card should be connected on some other pins, probably HSPI. It has not +yet been verified will that work.