Import of the watch repository from Pebble

2025-05-22 03:14:52 +00:00 · 2024-12-12 16:43:03 -08:00 · 2024-12-12 16:43:03 -08:00 · 3b92768480
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+### About
+
+Files in this folder (embedding/esp8266) are copied from
+`examples/project_template` of `esp_iot_rtos_sdk` and modified for JerryScript.
+You can view online from
+[this](https://github.com/espressif/esp_iot_rtos_sdk/tree/master/examples/project_template) page.
+
+
+### How to build JerryScript for ESP8266
+
+#### 1. SDK
+
+Follow [this](./docs/ESP-PREREQUISITES.md) page to setup build environment
+
+
+#### 2. Patch ESP-SDK for JerryScript
+
+Follow [this](./docs/ESP-PATCHFORJERRYSCRIPT.md) page to patch for JerryScript building.
+Below is a summary after SDK patch is applied.
+
+#### 3. Building JerryScript
+
+```
+cd ~/harmony/jerryscript
+# clean build
+make -f ./targets/esp8266/Makefile.esp8266 clean
+# or just normal build
+make -f ./targets/esp8266/Makefile.esp8266
+```
+
+Output files should be placed at $BIN_PATH
+
+#### 4. Flashing for ESP8266 ESP-01 board (WiFi Module)
+
+Steps are for `ESP8266 ESP-01(WiFi)` board. Others may vary.
+Refer http://www.esp8266.com/wiki/doku.php?id=esp8266-module-family page.
+
+##### 4.1 GPIO0 and GPIO2
+
+Before flashing you need to follow the steps.
+
+1. Power off ESP8266
+2. Connect GPIO0 to GND and GPIO2 to VCC
+3. Power on ESP8266
+4. Flash
+
+##### 4.2 Flashing
+
+```
+make -f ./targets/esp8266/Makefile.esp8266 flash
+```
+
+Default USB device is `/dev/ttyUSB0`. If you have different one, give with `USBDEVICE`, like;
+
+```
+USBDEVICE=/dev/ttyUSB1 make -f ./targets/esp8266/Makefile.esp8266 flash
+```
+
+
+### 5. Running
+
+1. Power off
+2. Disonnect(float) both GPIO0 and GPIO2
+3. Power on
+
+Sample program here works with LED and a SW with below connection.
+* Connect GPIO2 to a LED > 4K resistor > GND
+* Connect GPIO0 between VCC > 4K resistor and GND
+
+If GPIO0 is High then LED is turned on longer. If L vice versa.
+
+### 6. Optimizing initial RAM usage (ESP8266 specific)
+The existing open source gcc compiler with Xtensa support stores const(ants) in
+the same limited RAM where our code needs to run. 
+
+It is possible to force the compiler to 1)store a constant into ROM and also 2) read it from there thus saving 1.1) RAM.
+It will require two things though:
+1. To add the attribute JERRY_CONST_DATA to your constant. For example
+
+```C
+static const lit_magic_size_t lit_magic_string_sizes[] =
+```
+
+can be modified to
+
+```C
+static const lit_magic_size_t lit_magic_string_sizes[] JERRY_CONST_DATA =
+```
+
+That is already done to some constants in jerry-core. 
+
+1.1) Below is a short list:
+
+
+Bytes  | Name
+-------- | ---------
+928 | magic_strings$2428
+610 | vm_decode_table
+424 | unicode_letter_interv_sps
+235 | cbc_flags
+232 | lit_magic_string_sizes
+212 | unicode_letter_interv_len
+196 | unicode_non_letter_ident_
+112 | unicode_letter_chars
+
+Which frees 2949 bytes in RAM. 
+
+2. To compile your code with compiler that supports the `-mforce-l32` parameter. You can check if your compiler is 
+supporting that parameter by calling:
+```bash
+xtensa-lx106-elf-gcc --help=target | grep mforce-l32
+```
+If the command above does not provide a result then you will need to upgrade your compiler.