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ESP32 Dev Board program memory size?

PostPosted: Tue Jun 06, 2017 1:11 pm
by w5uxh
UPDATE: Daniel was not able to reply here from his phone, but kindly emailed me with the answer that I had missed in the data sheet:

ESP-WROOM-32 integrates 4 MB of external SPI flash.

Original query from me:
I just received the EzSBC Model ESP32-01 module ordered on ebay and have a question about how much program memory is actually provided. I have only scratched the surface of the documentation, so this is probably a dumb question, but:

The ebay page indicates the following:

Integrated 520 KB SRAM
Integrated 802.11BGN HT40 Wi-Fi transceiver, baseband, stack and LWIP
Integrated dual mode Bluetooth (classic and BLE)
16 MByte flash <----

and further down lists this: Supports external SPI flash up to 16 MB <----

My guess is the first statement about 16 MByte flash does not mean that there is 16MB of program flash (?) but there is still a related question:

When using Arduino to compile a web server example sketch, Arduino reports the following for the "ESP32 Dev Module":

Sketch uses 429271 bytes (32%) of program storage space. Maximum is 1310720 bytes.

The data sheets indicate that there is: 448 KB Internal ROM. If this is correct, then the sketch is actually using 95%, not 32%. Clarification would be helpful, how much program memory is really available?

I notice when downloading the sketch to the module (the web server demo works fine) the downloader mentions some compression being done. I have not been able to find any discussion of what is going on. If anyone can provide a link to some information about this compression, it would be appreciated.