Schematic Build Update
Worked for 13 mins 12 sec
Created a thread, a component
ER-TFT028A3-4
EastRising/BuyDisplay raw 2.8-inch 240x320 IPS TFT LCD panel, ST7789V controller, no touch, 50-pin 0.50 mm FPC, parallel/RGB/serial interfaces, nominal 2.8 V VCI/VDDI and approximately 70 mA white LED backlight.
Verify ER-TFT028A3-4 symbol
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The verified display interface, 2.8 V translation, charger limits, and GPIO remap are in place. Two hardware items remain blocked by missing authoritative geometry/electrical data—the IMU footprint and backlight LED string—so I’m independently checking the completed schematic and documentation before closing.
Worked for 2 mins 55 sec
Implemented the verified ER-TFT028A3-4 50-pin display interface, 2.8 V supply and level translation, 8-bit I80 GPIO mapping, and safe BQ24074 500 mA/349 mA charging configuration. Final ERC, passive, and schematic-readability checks are clean; no PCB layout work was performed.
Remaining blockers
- LSM6DS3TR-C: authoritative LGA-14 land-pattern geometry was not accessible, so no footprint was guessed.
- Backlight driver: the panel documentation does not provide sufficient LED string forward-voltage/topology data;
BL_PWMis reserved but the power stage remains intentionally incomplete. - Future USB-C advertised-current detection remains unpopulated; this revision is safely locked to 500 mA.
Updated files: Project Specification, Block Diagram, Firmware Getting Started, and Board Bring-Up Plan.
Resolve remaining blockers
Review power budget
Prepare PCB placement
Inspect display interface
Refine this doc
Ask about this doc
Firmware Getting Started
ESP-IDF target
ESP32-S3-WROOM-1-N8R8. Use USB Serial/JTAG or TinyUSB on fixed GPIO19 D− / GPIO20 D+; UART test access is intentionally omitted.
GPIO definitions
C
#define PIN_BOOT 0 #define PIN_RTC_INT 1 #define PIN_FUEL_ALERT 2 #define PIN_IMU_INT1 4 // reserved; hardware part blocked #define PIN_IMU_INT2 5 // reserved; hardware part blocked #define PIN_HAPTIC_EN 6 #define PIN_BL_PWM 7 // do not enable until backlight driver is completed #define PIN_I2C_SDA 8 #define PIN_I2C_SCL 9 #define PIN_LCD_D0 10 #define PIN_LCD_D1 11 #define PIN_LCD_D2 12 #define PIN_LCD_D3 13 #define PIN_LCD_D4 14 #define PIN_LCD_D5 15 #define PIN_LCD_D6 16 #define PIN_LCD_D7 17 #define PIN_LCD_WR 18 #define PIN_LCD_DC 21 #define PIN_CHG_STAT 43 #define PIN_USB_PGOOD 44 #define PIN_LCD_CS 47 #define PIN_LCD_RESET 48
I80 display
Use
esp_lcd_new_i80_bus() with bus_width=8 and data_gpio_nums ordered D0..D7. Create the panel IO with esp_lcd_new_panel_io_i80() using GPIO18 as wr_gpio_num, GPIO21 as dc_gpio_num, GPIO47 as CS, and a write-only bus (RD is hard-pulled high). Use the ST7789 panel driver via esp_lcd_new_panel_st7789(), hardware reset GPIO48, 240×320 geometry, and the initialization sequence required by the ER-TFT028A3-4/ST7789V production datasheet. Start with a conservative pixel clock and validate timing before increasing it.I2C/peripherals
Create one I2C master bus on GPIO8/9. Exactly one external pull-up pair exists. Initialize DRV2605L, MAX17048, RV-3028-C7, and VEML7700. LSM6DS3TR-C initialization and its address/interrupt handling remain blocked until the exact part is added. GPIO4/5 are reserved for INT1/INT2.
Interrupts and controls
- GPIO1: RTC interrupt, active-low/open-drain per device configuration.
- GPIO2: fuel-gauge alert.
- GPIO43: BQ24074 CHG open-drain status; low during first charge cycle and flashes on timer fault.
- GPIO44: BQ24074 PGOOD open-drain; low for valid input.
- GPIO6: DRV2605L enable.
- GPIO0: BOOT only; never repurpose.
- EN: hardware reset button/RC.
Backlight PWM
Reserve an LEDC PWM channel on GPIO7 but keep output low/high-impedance until the missing current-limited backlight power stage is completed and verified. Never connect the 70 mA backlight directly to an ESP32 GPIO.
Startup sequence
- Keep LCD CS inactive, RESET asserted, and BL_PWM off.
- Initialize status inputs and native USB.
- Initialize I2C and verify known addresses.
- Enable/configure DRV2605L.
- Initialize I80 bus and ST7789 panel while backlight remains off.
- Release panel reset, run initialization, draw test patterns.
- Enable backlight PWM only after the completed current driver is verified.
- Monitor CHG/PGOOD and reduce high-current activity during USB-current-limited charging tests.
ESP-IDF target
GPIO definitions
I80 display
I2C/peripherals
Interrupts and controls
Backlight PWM
Startup sequence
