Variants of D1 Mini with ESP8266

Overview

In this post I take a look at prototype boards for MCUs from Espressif. Espressif offers two popular micro-controller families: ESP8266 and ESP32. Those two SOCs have a lot in common, while the ESP32 is the stronger one with 2 main cores, higher performance, and more peripheral interfaces.

On the other hand the ESP8266 has lower power consumption and provides sufficient performance for many applications. Additionally, the ESP8266 family has a member called ESP8285 that provides internal flash memory, so that it can be used for very small boards, as no additional external flash is necessary.

Here is a short comparison table of these controllers: 

Feature	ESP8266	ESP32
architecture	Tensilica L106	Tensilica LX6
# main cores	1	2
WiFi MAC	yes	yes
Bluetooth MAC	no	yes
Ethernet MAC	no	yes
touch	no	yes
hall sensor	no	yes
SPI	2	4
PWM	software	hardware
waveform generator	no	yes

Both families provide much more features than shown in this short table. This table should give you just an impression of those architectures, in case you are not familiar with them.

One popular prototyping board with ESP8266 is the D1 mini offered by Wemos, which is also provide as a clone by other companies. The variants and versions of the D1 mini have subtle differences, we want to take a look at here.

Boards with ESP8266

D1 Mini:

• ESP8266
• 4 MB external flash integrated in metal package
• USB socket connect to UART0 TX/RX
• Reset button
• From Version 2.2.0 to version 2.3.0 the USB socket moved from back to front 
• one LED

D1 Mini Lite:

• ESP8285
• 1MB internal flash
• USB socket connect to UART0 TX/RX 
• Reset button
• one LED

Mini32:

• Controller: ESP32
• Flash: 4MB
• USB socket is connected to UART TX only
  (Update: this observation is probably related to a broken device. A sample of a similar looking clone without branding did not show this limitation. The clone had an additional LED, so it has not the exact schematic. But the additional LED is just a supply monitoring LED.)
• Reset button
• Pads have same spacing, but are assigned differntly. The critical pads are assigned the same: VCC, GND, TX, RX, 3,3V, RST
• 2 LEDs