nRF52: Write flash in 2k blocks (not 4k) as SD 6.1.1 can crash (proba…

…bly good for earlier SD too)

ChangeLog

@@ -2,6 +2,7 @@
             nRF52: Lower expected BLE XTAL accuracy to 50ppm (can improve BLE stability on some Bangle.js 2)
             Emulator: force stack alignment of 'data' variable when accessing ArrayBuffers (fix #2463)
             Swapped GCC version from 8.2.1 to 13.2.1 (fix #2455)
+            nRF52: Write flash in 2k blocks (not 4k) as SD 6.1.1 can crash (probably good for earlier SD too)
 
      2v21 : nRF52: free up 800b more flash by removing vector table padding
             Throw Exception when a Promise tries to resolve with another Promise (#2450)

targets/nrf5x/jshardware.c

@@ -2641,8 +2641,8 @@ void jshFlashWrite(void * buf, uint32_t addr, uint32_t len) {
       uint32_t l = len;
 #ifdef NRF51_SERIES
       if (l>1024) l=1024; // max write size
-#else
-      if (l>4096) l=4096; // max write size
+#else // SD 6.1.1 doesn't like flash ops that take too long so we must not write the full 4096 (probably a good plan on older SD too)
+      if (l>2048) l=2048; // max write size
 #endif
       len -= l;
       while ((err = sd_flash_write(((uint32_t*)addr)+wordOffset, ((uint32_t *)buf)+wordOffset, l>>2)) == NRF_ERROR_BUSY && !jspIsInterrupted());