mule-attiny: i2c_flash: support flashloader read-only mode

After entering the flashloader it is safe to set it into read-only mode
(by pulling the boot request gpio back low) until the fw_flash() routine
is actually called. This avoids having any i2c process, by mistake, write
to the wire (flash unwanted/invalid data).

Signed-off-by: Farouk Bouabid <farouk.bouabid@theobroma-systems.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py b/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
index c424808..c867558 100755
--- a/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
+++ b/mule-attiny/i2c-flash/src/mule-attiny_i2c_flash/i2c_flash.py
@@ -54,6 +54,16 @@ class BootModeController:
         sleep(0.1)
 
         self.__flashMode = True
+        self.enterRoMode()
+
+    # Flashloader sub-mode (read-only: read bootloader data)
+    def enterRoMode(self):
+        if self.__flashMode:
+            self.__bootReq.set_value(0)
+
+    def exitRoMode(self):
+        if self.__flashMode:
+            self.__bootReq.set_value(1)
 
     def exitFlashloader(self):
         if self.__bootReq.is_requested():
@@ -178,8 +188,9 @@ def main():
     )
 
     try:
-        # Request flashloader through bootloader
+        # Request flashloader through bootloader (Set to read-only-mode by default)
         bootCtrl.enterFlashloader()
+        bootCtrl.exitRoMode()
         ret = fw_flash(_bin, args.i2c_bus)
 
     except Exception as err: