Here is my Schematic review :
- I see DS4432U+ OUT0 being used for TPS40305 control, but does the OUT1 being used somewhere ? (if not use, better not creating a signal out of the package to give ambiguity...)
- where the 5V is generated ? I see +3V3 (U11), 1V8 (U5) and 0V8 (U6) being generated from 5V, and BM1397 VDD (alias of TPS40305 VOUT) being generated from VIN_M (the monitored VIN), but nowhere the 5V beoing generated...
- on the ESP, I think you inverted TX/RX, please double check it
- can you add pin header and TP for debug purpose on the 3V3 RX/TX/RST, (additionnaly to J3), and add also I2C SDA/SCL signal on this debug pin header ?
- can you use an optional (with a serial 0R resistor) signal from a CLK_OUT of the ESP (pin 13/14/34/33/32 up to you) going to the BM1397 CLKI instead of the U1 one. I may want to try later if MCU can generate this clock by SW so we have control on the hashrate of the BM1397...
- on the BM1397 you pulled down BI (with R4) are you sure it will not being used ? on BM1385 datasheet it is noted as a Busy Input (internal schmit trugger and pull down). Maybe you can link it to a GPIO of the MCU, we will see later if needed. (and add the 3V3 signal to the debug pin header too).
- for the voltage level translators (U2/U3/U4), I used to use TSX0104 in my previous design, it is easy to use because bidirectionnal. Did you consider them ?
- for EMC2101, the ALTER#/TACH pin can be configured as input (TACH monitor to mesure Fan RPM) or output (ALERT# signal to trigger an IRQ on MCU when special temp/tach conditons are met). I see more value having an ALERT# signal from it to the MCU to trigger an interrupt for Temperature Critical exceeded (with hysteresis to deassert the signal). The FAN RPM is not very usefull for us. Also EMC2101 porpose a Look-up Table of 8 stages so we can control by hardware FAN speed accoding to BM1397 internal temperature. Maybe what you can do, is link the EMC2101 ALERT#/TACH pin to a MCU GPIO, and the FAN TACH to another MCU GPIO (be careful of voltage level here), and SW will be able to configure EMC2101 in TACH reading for some seconds, by propagating the FAN signal, then switch back to ALERT interrupt for a longer period (1h ?). So most of the time we use Interrupt monitor, and only once in a while do a fAN RPM measurement for UI needs...
- it would be usedfull to have the BM1397 VDD on a ESP ADC input to measure the BM voltage
- it would be usefull to have the TPS40305 PGOOD linked to a ESP GPIO to know if Power is Good
I checked in an update to the schematic on the max_v2 branch with all of these changes. I'm still a little iffy on the level shifting for the interface to CLKI and the fan ALERT.
Great, did another check :
- for the CLKI signal directly on the ESP, please add a 0R (or a 33R as it is a clock) serial resistor to disconnect this signal by HW.
- on J3, maybe better to put 1V8 on this debug connector because all signals are on 1,8V level (and now the 3V3 is available on J6)
- maybe better using the 4th TSX0104 line for the CLKI signal instead of BI, and put BI on the voltage divider ? BI is low freq signal. Waht do you think about this ? I have the feeling high freq signal are better ont the TSX0104 (otherwise we should better use voltage divider for all signal from ESP to BM).
- on the Fan design, I understad you plan to use a 5V FAN directly powered by our input VIN,
* Firstly, Fan usually generate lot of noise, we should consider filtering this noise.
* Secondly, we will control this fan with a 3V3 level PWM, and the 5V TACH signal is directly on the EMC2101 pin. Maybe better using a TSX0102 for level converting 3V3/5V these 2 signals.
* Finnaly, as for this dual signal we are not sure yet of the final usage, I would do a more modular (optioal) HW design using 0R resistors. For exemple:
a/ 1 signal from the FAN TACH_3V3 (from J4 after going through TSX0102) connected to a dedicated ESP GPIO (with the 0R resistor so we can unconnect it)
b/ 1 signal from the FAN TACH_3V3 (from J4 after going through TSX0102) connected to the EMC2101 ALERT#/TACH pin (with another 0R resistor so we can unconnect it)
c/ 1 signal from the EMC2101 ALERT#/TACH pin connected to a dedicated ESP GPIO (diffeent from a/) (also with a 0R resistor so we can unconnect it)
this way we can choose by HW (some 0R resistor) the logic we want to try during the development phase.