From e836c4b9e78cc3892cdebf8126cb650f1b91ed37 Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <sadeep@asciimx.com>
Date: Thu, 8 Jan 2026 22:28:37 +0800
Subject: Tighten prose.

---
 _log/e-reader.md | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

(limited to '_log/e-reader.md')

diff --git a/_log/e-reader.md b/_log/e-reader.md
index 69b1e96..45363f7 100644
--- a/_log/e-reader.md
+++ b/_log/e-reader.md
@@ -1,12 +1,12 @@
 ---
-title: 512 KB e-reader
+title: 512KB e-reader
 date: 2023-10-24
 layout: post
 project: true
 thumbnail: thumb_sm.png
 ---
 
-First project with e-paper displays and ESP32.
+First project with e-paper.
 
 <video style="max-width:100%;" controls="" poster="poster.png">
   <source src="ereader.mp4" type="video/mp4">
@@ -15,13 +15,13 @@ First project with e-paper displays and ESP32.
 ESP-WROOM-32, 7.5" Waveshare e-paper display, three-button interface
 (prev/next/sleep).
 
-Memory: 512KB SRAM + 4MB flash. Internal 4 MB flash unsuitable for storing
-books due to P/E cycle limits. HTTP Range requests for on-demand bitmap
-streaming. Progress saved to RTC memory to survive deep sleep without flash
-wear.
+Memory: 512KB SRAM + 4MB flash. Internal flash unsuitable for storing books due
+to P/E cycle limit. Used HTTP Range requests to stream them on-demand.
+Progress saved to RTC memory to survive deep sleep without flash wear.
 
-EBM format: Raw bitmap sequence. 1 byte = 8 pixels, 1 page = 48 KB (display
-resolution), headerless. Optimized for HTTP Range requests:
+PDFs are rasterized and stored as sequences of bitmaps on a server. 1 byte = 8
+pixels, 1 page = 48KB (display resolution), headerless. Optimized for Range
+requests without server-side logic:
 
 ```
 int r0 = ((page_n - 1) * PAGE_SIZE);
@@ -35,8 +35,9 @@ esp_http_client_set_header(http_client, "Range", buf);
 esp_http_client_perform(http_client);
 ```
 
-Page buffer: Three pages (prev/current/next) in RAM—maximum possible. On
-request: cycles buffer, updates screen, prefetches next page.
+Three pages (prev/current/next) held in a buffer—maximum possible. Upon
+request, embedded software cycles the buffer, updates the screen, prefetches
+the next page.
 
 ```
 c_page_num++;
@@ -50,12 +51,14 @@ epd_draw_async(pages[c_page_num % PAGE_LEN], PAGE_SIZE);
 epd_draw_await();
 ```
 
-Responsiveness: inadequate. Scheduling GPIO, SPI, and HTTP tasks on a single
-thread causes input lag. Pinned GPIO/SPI tasks to one core and the HTTP task to
-the other.
+System isn't as responsive as I'd hoped. Scheduling GPIO, SPI, and HTTP tasks
+on a single thread causes input lag. Pinned GPIO/SPI tasks to one core and the
+HTTP task to the other.
 
-Better, but screen updates block user input. Moved SPI buffers to DMA and made
-transfers async. Few more cycles saved.
+Better, but screen updates block user input. 
+
+Moved the SPI buffers to DMA and made the transfers async. Few more cycles
+saved.
 
 Can't think of anything else.
 
-- 
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