stm32/WEACTV20_F411: Add variant for FLASH_4MB.

Signed-off-by: Andrew Leech <andrew@alelec.net>

ports/stm32/boards/WEACTV20_F411/board.json

@@ -0,0 +1,18 @@
+{
+    "deploy": [
+        "../PYBV10/deploy.md"
+    ],
+    "docs": "",
+    "features": [],
+    "images": [
+        "WEACTV20_F411.jpg"
+    ],
+    "mcu": "stm32f411",
+    "product": "WeAct v2.0 'blackpill'",
+    "thumbnail": "",
+    "url": "https://stm32-base.org/boards/STM32F411CEU6-WeAct-Black-Pill-V2.0.html",
+    "variants": {
+        "FLASH_4MB": "SPI Flash 4MB"
+    },
+    "vendor": "WeAct Studio"
+}

ports/stm32/boards/WEACTV20_F411/mpconfigboard.h

@@ -8,7 +8,9 @@
 
 // Set to 1 to use internal flash, set to 0 to use external SPI flash
 // You also need to set the size of the flash later in this header
+#ifndef MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
 #define MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE (1)
+#endif
 
 // some users having issues with FLASH_LATENCY_2, so set to 3
 // from https://forum.micropython.org/viewtopic.php?t=7154
@@ -93,7 +95,9 @@
 // 4MB => 32MBit
 // 8MB => 64MBit
 // 16MB => 128MBit
+#ifndef MICROPY_HW_SPIFLASH_SIZE_BITS
 #define MICROPY_HW_SPIFLASH_SIZE_BITS (128 * 1024 * 1024)
+#endif
 
 #if !MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
 

ports/stm32/boards/WEACTV20_F411/mpconfigvariant_FLASH_4MB.mk

@@ -0,0 +1 @@
+CFLAGS += -DMICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE=0 -DMICROPY_HW_SPIFLASH_SIZE_BITS="(32 * 1024 * 1024)"