2.8 inch IPS TFT LCD 240x320 Pixels with MCU Interface with IC ST7789V P028B126-IPS

Product Overview

P028B126-IPS is a 2.8" IPS TFT LCD display module with a resolution of 240RGB(H)×320(V), a contrast ratio of 1200:1, and a luminance of 300 nit, connected via a 24-pin FPC and driven over an MCU 8-bit parallel interface using the ST7789V driver IC. The display mode is Normally Black with all-direction viewing angle coverage, and the module operates from −20°C to +70°C. The 1200:1 contrast ratio is the defining specification of this IPS variant — approximately 2.4× higher than a standard TN panel at the same size class — and is the primary reason to select this module over non-IPS alternatives in applications where color accuracy and off-axis readability matter.

The active display area is 43.20(H)×57.60(V)mm inside an outline of 50.00×69.20×2.30mm. Pixel pitch is 0.180(H)×0.180(V)mm — exactly square — with RGB Vertical Stripe arrangement and 262K color depth (18-bit). The backlight uses an LED side-light configuration within the 2.30mm module depth.

IPS Panel Technology and Contrast Advantage

The IPS (In-Plane Switching) cell structure in this 2.8-inch IPS LCD module aligns liquid crystal molecules parallel to the substrate plane, eliminating the grayscale inversion that TN panels exhibit at oblique viewing angles. In practice, this means the displayed image — including dark-background UI elements, status indicators, and color-coded readouts — renders consistently whether viewed straight-on or at angles exceeding 60° off-axis horizontally or vertically.

The 1200:1 contrast ratio, combined with the Normally Black mode, produces deep blacks when pixels are off. This is measurable: at 300 nit white luminance, black luminance measures at approximately 0.25 cd/m², which keeps dark UI elements dark in moderately lit environments. TN panels at this size class typically achieve 250:1 to 500:1; the 1200:1 figure is characteristic of IPS and is verifiable against the datasheet.

Interface and GPIO Requirements

The MCU 8-bit parallel interface uses 8 data lines (D[7:0]) plus control signals CS, RS (D/C), WR, RD, and RST — approximately 13–14 GPIO pins from the host MCU. This interface achieves higher frame throughput than SPI at equivalent clock speeds: a full 240×320 frame at 16-bit color requires writing 153,600 bytes, which completes in approximately 12ms at an 8-bit bus with a 100ns write cycle (the ST7789V minimum), yielding around 80 fps theoretical maximum. In practice, MCU bus overhead reduces this, but 30–60 fps full-frame rates are achievable on STM32 FSMC/FMC with DMA.

The 24-pin FPC connector carries data lines, control signals, power supply pins (VDD, IOVDD), and backlight connections (LEDK/LEDA). Logic voltage is typically 3.3V for the ST7789V; confirm the IOVDD range in the datasheet before connecting a 5V MCU GPIO directly. The RD pin is used for reading back register values; if read-back is not required in the application, RD can be tied high to free one GPIO.

Dimensions and Square Pixel Geometry

The pixel pitch is 0.180(H)×0.180(V)mm — exactly square. This simplifies UI development: circles render as circles, font aspect ratios match their design intent, and image scaling from standard square-pixel sources requires no correction. The effective pixel density is approximately 141 ppi, which renders 8pt system fonts legibly and supports small icon assets (16×16, 24×24 px) without noticeable aliasing.

The module outline is 50.00×69.20×2.30mm, and the active area is 43.20×57.60mm, leaving a 3.40mm inactive border on the horizontal edges and 5.80mm on the vertical edges. PCB and enclosure designs should account for this border when defining the display window cutout. At 2.30mm total depth, the module fits enclosures with tight Z-axis constraints, consistent with the 2.4" SPI module in the same product family.

ST7789V Driver IC

The ST7789V integrates a 240×320×18-bit frame buffer and display controller, supporting MCU 8-bit, MCU 16-bit, SPI, and QSPI interfaces — though this module is configured for MCU 8-bit only. The IC handles all display refresh timing internally; after each frame is written, the panel sustains the image without further MCU intervention. This allows the host processor to enter a low-power state between UI updates without the display going blank.

The ST7789V supports a partial display mode (PTLAR/PTLON commands) that restricts active refresh to a defined row range, reducing backlight power in applications that update only a portion of the screen. It also supports display inversion (INVON/INVOFF), color depth switching between 12-bit, 16-bit, and 18-bit per pixel, and display rotation via the MADCTL register — allowing portrait or landscape orientation to be set in firmware without rotating the physical module. Open-source ST7789V drivers are available for STM32 HAL, ESP-IDF, Arduino, and LVGL's display driver layer.

Luminance and Operating Environment

Luminance is 300 nit, suited for indoor environments and covered-outdoor use where ambient illuminance stays below approximately 1,000 lux. In direct sunlight (50,000–100,000 lux ambient), a 300 nit panel will wash out regardless of contrast ratio; applications in that environment should specify a high-brightness variant (800 nit or above) or apply an anti-reflective coating combined with optical bonding to reduce the surface reflection loss. The IPS panel's all-direction viewing angle does not compensate for insufficient luminance against high ambient light.

Operating temperature is −20°C to +70°C; storage temperature is −30°C to +80°C. These ratings cover standard indoor industrial, medical instrument, and consumer device environments. For cold-start conditions below −20°C, IPS panels exhibit slower liquid crystal response times than TN panels at low temperature — evaluate the cold-start display latency in the target thermal environment before finalizing the specification.

Medical and Handheld Instrument Applications

The all-direction IPS viewing angle and 1200:1 contrast ratio make this IPS TFT LCD module suited for handheld medical instruments where the operator's viewing angle relative to the screen is not fixed. Blood glucose meters, pulse oximeters, portable ECG monitors, and infusion controllers are common applications at the 2.8" size class; the MCU 8-bit interface connects directly to the application MCU (STM32L4, nRF5340, or similar) without a separate display controller, keeping the BOM compact.

The 240×320 portrait orientation at 2.8" provides enough screen area to display two to three waveform channels with parameter readouts simultaneously in a single screen layout, which is a common requirement in bedside monitoring handhelds. For IEC 60601-1 medical device compliance, the module itself does not carry a medical certification; system-level electrical safety (isolation, leakage current) must be addressed in the host device design.

Industrial HMI and Embedded Panel Applications

In compact industrial HMI panels, the 50.00×69.20mm outline fits standard 2.8" front-panel cutouts used in handheld PLC programmers, field calibrators, and data loggers. The MCU 8-bit interface is directly supported by the FSMC/FMC peripheral on STM32 microcontrollers, which maps the display to the MCU's memory address space and enables DMA-driven frame writes without CPU involvement — a standard approach for achieving smooth UI refresh rates on Cortex-M4/M7 class devices.

The Normally Black IPS display mode is preferred in industrial indicator applications: a power-loss event results in a uniformly black screen rather than a white or partially illuminated state, which operators interpret unambiguously as "off." The all-direction viewing angle ensures readability across the range of mounting orientations used in panel-mount and handheld industrial enclosures without requiring the operator to align their viewing angle to the panel's optimal direction.

Selection Comparison: IPS vs. TN at 2.8"

The primary selection decision at 2.8" QVGA (240×320) is between IPS and TN panel technology. TN variants (such as the SPI-interface P024BFT01-40 at 2.4") offer lower unit cost, lower power consumption in high-refresh applications, and faster liquid crystal response at low temperatures. IPS variants trade those attributes for the 1200:1 contrast ratio, all-direction viewing angle, and color accuracy — the combination that makes P028B126-IPS the correct choice when the display shows color-coded data, is viewed from variable angles, or is used in a product where display quality is visible to end users.

Within the 2.8-inch TFT LCD module segment, secondary selection axes include interface type (MCU 8-bit here vs. SPI on lower-cost variants), pin count (24 pins vs. 13–20 for SPI modules), and outline dimensions. The MCU 8-bit interface requires more GPIO but delivers higher throughput than SPI — the decision between them is determined by the host MCU's available GPIO and the application's required frame rate. At 240×320, SPI at 40 MHz achieves approximately 25–30 fps; MCU 8-bit with DMA on STM32 FSMC achieves 60+ fps.

Full Parameter Table

Frequently Asked Questions

• ●Why choose MCU 8-bit over SPI for the ST7789V at 240×320?

  The MCU 8-bit parallel interface transfers 8 bits per write cycle, versus 1 bit per clock edge for standard SPI. At the ST7789V's minimum 100ns write cycle, the 8-bit bus delivers a theoretical maximum of 80 MB/s, versus approximately 5 MB/s for SPI at 40 MHz. For a 240×320 frame at 16-bit color (153,600 bytes), MCU 8-bit completes a full-frame write in approximately 2ms; SPI at 40 MHz takes approximately 31ms. The practical impact: MCU 8-bit with STM32 FSMC and DMA achieves 60+ fps full-frame refresh for smooth animation and video; SPI is limited to 25–30 fps under the same conditions. The trade-off is GPIO count — MCU 8-bit requires ~13 pins versus 4–6 for SPI. Select MCU 8-bit when frame rate matters; select SPI when GPIO is the binding constraint.
• ●How does the 1200:1 contrast ratio compare to standard TN modules, and is it measurable?

  The 1200:1 contrast ratio is the ratio of white luminance to black luminance measured perpendicular to the panel surface in a dark room. At 300 nit white, black luminance measures approximately 0.25 cd/m². Standard TN panels at 2.4"–2.8" typically specify 250:1 to 500:1, yielding black luminance of 0.6–1.2 cd/m² at the same white level — visibly lighter. The difference is most apparent in dark-background UIs (common in medical and industrial instruments), where TN panels show a milky dark-gray rather than black. IPS black is measurably deeper. You can verify this with a spot luminance meter (Konica Minolta LS-150 or equivalent) by measuring white and black full-screen test patterns at normal incidence; the ratio should fall within ±15% of the 1200:1 spec under controlled conditions.
• ●Which STM32 families support MCU 8-bit parallel LCD via FSMC/FMC?

  STM32 families with FSMC (Flexible Static Memory Controller) or FMC (Flexible Memory Controller) support MCU 8-bit parallel LCD natively: STM32F1 (FSMC on F103ZE and larger), STM32F2, STM32F4, STM32F7, STM32H7, and STM32L4 (select variants with FMC). The display is mapped to a FSMC/FMC bank address, and frame data is written via DMA to that address, bypassing the CPU. STM32CubeMX generates the FSMC/FMC configuration; the display timing parameters (address setup time, data setup time) must be set to match the ST7789V's WR cycle timing (minimum 100ns write, 15ns setup). Arduino-class MCUs (ATmega328P) do not have a hardware parallel bus controller and would require bit-banged 8-bit writes, which limits frame rate to single-digit fps — use SPI mode for Arduino targets instead.
• ●Can a touch panel be added, and which touch controller ICs are compatible?

  The P028B126-IPS is a display-only module. A resistive or projected-capacitive touch panel can be added on top of the display glass. The active area is 43.20×57.60mm — confirm that the touch sensor's active zone matches before ordering. For resistive touch, the XPT2046 (SPI, compatible with many STM32 and Arduino designs) is the standard controller for 2.8"–3.5" panels and is used in many pre-integrated 2.8" LCD+touch shield assemblies. For PCAP touch, FocalTech FT6206 or Goodix GT911 (both I²C) are common choices at this size. Note that the 24-pin FPC on this module does not include touch signal lines; a separate touch panel FPC and controller IC on the host PCB are required. If a pre-integrated display+touch solution is preferred, request the touch-integrated variant from the supplier.
• ●What LVGL configuration is recommended for this module on an STM32?

  For LVGL on STM32 with MCU 8-bit parallel via FSMC: configure a full or partial framebuffer in SRAM. A full 240×320 buffer at 16-bit color requires 153,600 bytes (150 KB) — within STM32F429 (256 KB SRAM) or STM32H743 (1 MB SRAM), but exceeds STM32F103 (20–64 KB). For lower-SRAM targets, use LVGL's two-buffer partial-refresh mode with each buffer sized at 240×40 pixels (19,200 bytes each, 37.5 KB total), which allows DMA transfer of one buffer while LVGL renders into the other. Set lv_conf.h: LV_COLOR_DEPTH 16, LV_HOR_RES_MAX 240, LV_VER_RES_MAX 320. The ST7789V flush callback writes the dirty rectangle via FSMC DMA using the CASET/RASET/RAMWR command sequence. Enable LV_USE_GPU_STM32_DMA2D on STM32F4/H7 targets for hardware-accelerated blending.