The latest articles on DEV Community by Amken USA (@amken3d). https://dev.to/amken3d https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F2295668%2F0809be74-b0c8-49f8-8849-8b0e7b3fa57b.png https://dev.to/amken3d en Amken USA Sun, 24 May 2026 12:59:00 +0000 https://dev.to/amken3d/why-i-wrote-an-entire-rp2350-sdk-in-pure-arm-assembly-2jf5 https://dev.to/amken3d/why-i-wrote-an-entire-rp2350-sdk-in-pure-arm-assembly-2jf5 <p>This post lives at the canonical source on ticktrace.io. Read it there for the latest version.</p> <p><strong><a href="https://www.ticktrace.io/blog/why-pure-assembly/" rel="noopener noreferrer">Why I wrote an entire RP2350 SDK in pure ARM assembly</a></strong></p> <p>ticktrace is a pure-assembly firmware SDK for the Raspberry Pi RP2350. The default blinky is just 1192 bytes. The toolchain you<br> install to build it is 5.6 MB. No <code>gcc</code>, no <code>newlib</code>, no <code>libstdc++</code>. The most minimalist, yet powerful SDK for the RP2 family.</p> <h2> What pure assembly actually looks like </h2> <p>People hear "assembly" and picture something unreadable. Here is the entire <code>main</code> function of the default firmware. This is the actual source, line for line, from <a href="https://github.com/ticktrace-sdk/rp-asm/blob/main/src/main.S" rel="noopener noreferrer"><code>src/main.S</code></a>:<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code> .thumb_func .global main main: @ ---- Clock tree bring-up --------------------------------------------- bl xosc_init @ XOSC stable bl pll_sys_150_mhz @ pll_sys = 150 MHz bl pll_usb_48_mhz @ pll_usb = 48 MHz bl clocks_init @ wire muxes bl tick_init @ 1 MHz tick to TIMER0/1/WDG bl watchdog_disable @ explicit safe state @ ---- Peripheral init at the new clock rate --------------------------- bl gpio_led_init @ LED on GP25 bl uart0_init @ wrong baud (computed for 12 MHz) bl clocks_post_pll_uart_baud_fixup @ fix to 150 MHz divisors ldr r0, =banner bl uart0_puts .Lloop: bl gpio_led_toggle @ 3-cycle inner body (subs + bne) at 150 MHz = 20 ns / iteration. @ DELAY_COUNT = 12_500_000 -&gt; 250 ms half-period -&gt; ~2 Hz blink. ldr r0, =DELAY_COUNT_150MHZ 1: subs r0, #1 bne 1b b .Lloop </code></pre> </div> <p>Read the full version on the blog.There is also an entire 14 chapter book that walks you through the basics of Assembly on this family of microcontroller.</p> <p>Repo: <a href="https://github.com/ticktrace-sdk/rp-asm" rel="noopener noreferrer">github.com/ticktrace-sdk/rp-asm</a><br> Site: <a href="https://www.ticktrace.io" rel="noopener noreferrer">ticktrace.io</a><br> Book: <a href="https://www.ticktrace.io/book" rel="noopener noreferrer">Learning Assembly with ticktrace</a></p> iot assembly arm raspberrypi