ESP32 Forum

Hi all,
I have 2 questions, may be you can help me
1. when I connect TDK using jumper, PSRAM does not work, if TDK is not connected it does work, but obviously I cannot use debugger which I need, is there solution?
2.I am new to ESP32 and we want to test next design : write 2.5Mbytes to the PSRAM, using FPGA then get the data to ESP32 for transmitting over WiFi, but to this I need pins: GPI016, SDO0-3,SRAM CLK at high impedance, when FPGA writes to psram, is there way doing so at run time (enabling disabling psram on the fly)?

thanks

1. What do you mean by 'TDK'?
2. That's pretty hard... the ESP32 accesses flash and PSRAM through more-or-less the same lines, so if you need to write directly to PSRAM, you either have to stop just about all processes in the ESP32, or you need to somehow disconnect the PSRAM chip from the ESP32. As an alternative, can you perhaps send the data to the SDIO or SPI slave port of the ESP32 and write it to RAM (or directly send it) from there?

It would make more sense to have separate psram connected to fpga only and connect fpga to esp32 with hspi/vspi.

thanks for replies
we would like to :
1.put ESP32 to light sleep
2. transfer data to psram from FPGA (quad spi 200 Mbit/sec, 0.1sec).
3. switch FPGA off, (saves a lot of battery time life)
4. then transfer the data from PSRAM over WiFi (TCP, 2sec)
we did not success yet, on logic analizer we see the FPGA is writing to PSRAM, but when ESP32 returns from sleep, the data is not there.

That's possibly because the ESP32 employs a cache for flash and PSRAM; you're reading data from the cache instead of from psram. I'd suggest you to call esp_spiram_writeback_cache() before going to light sleep to flush data to psram, and call it again after waking up again to make sure any data from the FPGA gets picked up correctly.