Delete unused images

src/gpio.md

@@ -141,7 +141,7 @@ By using layers of code that isolate the differences between microcontrollers (l
 
 Here's how we layer the code in Mynewt...
 
-![Mynewt and BL602 IoT SDK Layers](https://lupyuen.github.io/images/gpio-stack.png)
+![Mynewt and BL602 IoT SDK Layers](https://lupyuen.github.io/images/gpio-stack.jpg)
 
 1.  __Main Function__: We've seen the Main Function at the top of the article... It lights up the Blue LED.
 

src/lisp.md

@@ -1150,7 +1150,7 @@ The custom blocks were inspired by __MakeCode for BBC micro:bit__...
 
 -   [__MakeCode__](https://makecode.microbit.org/)
 
-![uLisp Code Generator](https://lupyuen.github.io/images/lisp-generate.png)
+![uLisp Code Generator](https://lupyuen.github.io/images/lisp-generate.jpg)
 
 # Code Generator for uLisp
 
@@ -1436,7 +1436,7 @@ What if we...
 
 1.  To allow embedded developers to __preview their BL602 Blockly Apps in the Web Browser__?
 
-![BL602 Simulator with uLisp WebAssembly](https://lupyuen.github.io/images/lisp-simulator.png)
+![BL602 Simulator with uLisp WebAssembly](https://lupyuen.github.io/images/lisp-simulator.jpg)
 
 Read the article...
 

src/lora.md

@@ -632,7 +632,7 @@ Let's capture and visualise our LoRa Packet with [__Airspy R2 SDR__](https://www
 
 1.  Our __LoRa Packet should scroll down__ like so...
 
-![CubicSDR software with Airspy R2 SDR](https://lupyuen.github.io/images/lora-sdr4.png)
+![CubicSDR software with Airspy R2 SDR](https://lupyuen.github.io/images/lora-sdr4.jpg)
 
 _CubicSDR software with Airspy R2 SDR_
 

src/lorawan.md

@@ -464,7 +464,7 @@ We shall study the source code and learn how the LoRaWAN Driver is called by our
 
 Our BL602 Driver for LoRaWAN has layers (like Onions, Shrek and Kueh Lapis): __Application Layer, Node Layer and Medium Access Control Layer__...
 
-![BL602 LoRaWAN Driver](https://lupyuen.github.io/images/lorawan-driver.png)
+![BL602 LoRaWAN Driver](https://lupyuen.github.io/images/lorawan-driver.jpg)
 
 1.  [__Application Layer: `lora_app.c`__](https://github.com/lupyuen/lorawan/blob/main/src/lora_app.c)
 
@@ -622,7 +622,7 @@ And that's how our LoRaWAN Driver sends a __Join Network Request__...
 
 LoRaWAN Firmware → Application Layer → Node Layer → Medium Access Control Layer → LoRa Transceiver Driver!
 
-![Medium Access Control Layer](https://lupyuen.github.io/images/lorawan-driver5.png)
+![Medium Access Control Layer](https://lupyuen.github.io/images/lorawan-driver5.jpg)
 
 ## Join Network Response
 
@@ -1291,7 +1291,7 @@ If our LoRaWAN Gateway didn't receive the data packet from BL602, here are some
 
     Here's the __Join Network Request__ transmitted by BL602 with RFM90...
 
-    ![Join Request](https://lupyuen.github.io/images/lorawan-sdr1.png)
+    ![Join Request](https://lupyuen.github.io/images/lorawan-sdr1.jpg)
 
     And here's the __Join Network Response__ returned by our WisGate D4H LoRaWAN Gateway...
 

src/wasm.md

@@ -311,7 +311,7 @@ Oh yes we have ways of __making uLisp talk to BL602 Simulator__... From WebAssem
 
 Here's one way: A __JSON Stream of BL602 Simulation Events__...
 
-![BL602 Simulator Design](https://lupyuen.github.io/images/lisp-simulator.png)
+![BL602 Simulator Design](https://lupyuen.github.io/images/lisp-simulator.jpg)
 
 _What's a BL602 Simulation Event?_
 
@@ -1263,7 +1263,7 @@ Which makes this design __harder to reuse__ for other kinds of BL602 Firmware (l
 
 To fix this, we apply [__Inversion of Control__](https://en.wikipedia.org/wiki/Inversion_of_control) and flip the design, so that __uLisp no longer controls the simulator directly__...
 
-![BL602 Simulator Design](https://lupyuen.github.io/images/lisp-simulator.png)
+![BL602 Simulator Design](https://lupyuen.github.io/images/lisp-simulator.jpg)
 
 And we get the __chosen design of our BL602 Simulator__.