Ft232h sync fifo

IndraSetu

pi pico <-> ft232h

GPIO2 -> CLKOUT

GPIO3 -> RXF#

GPIO4 -> TXE#

GPIO5 -> OE#

GPIO6 -> RD#

GPIO7 -> WR#

GPIO8 -> BIT0

3v3 + 3.3v -> ili9341 VCC -> LED ( this is for the lcd back light will be only be labled as led ) needs 3v3 volts from both the chips to balance current draw.

pi pico -> ili9341

Sending data which is emiting from pc through ft232h into pi pico with the help of PIO state machine

(PC + FT232H) -> Pi Pico

https://ftdichip.com/wp-content/uploads/2023/09/DS_FT232H.pdf page9

https://ftdichip.com/wp-content/uploads/2020/08/TN_167_FIFO_Basics.pdf page15

IndraSetu: High-Speed 60 MHz Synchronous FIFO Bridge

IndraSetu is an open-source hardware bridge PCB that connects a PC to a Raspberry Pi Pico (RP2040) using an FTDI FT232H in 60 MHz FT245 Synchronous FIFO mode, while driving an ILI9341 2.8" SPI TFT LCD.

Data emitted from the PC over USB is received by the FT232H, read by the Pi Pico's programmable I/O (PIO) state machine at high bandwidth, and rendered directly onto the ILI9341 display.

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1. PCB Stackup (4-Layer Controlled Impedance)

To ensure high signal integrity at 60 MHz, this board uses a 4-layer PCB stackup:

Why 4 Layers?

• Interleaved Ground Planes: Sandwiches signal traces between unbroken ground reference planes to minimize electromagnetic interference (EMI) and cross-talk.
• Controlled Return Paths: At 60 MHz, fast signal edges require immediate return paths through the nearest reference plane to prevent ground bounce and ringing.

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2. On-Board Discrete Components (BOM)

In addition to the socket headers for the three main modules (Pi Pico, FT232H, and ILI9341), the board features discrete helper components for power distribution, reverse-current protection, and power rail stabilization:

A. Backlight Power-Sharing Circuit

The ILI9341 display backlight draws noticeable current. To balance the load so neither the Pico nor the FT232H supply is overloaded, the board splits current between both 3.3V supplies:

• R1 & R2 — 10 Ω Current-Balancing Resistors (0603 SMD):
  • Part Number: Bourns CR0603-FX-10R0ELF (100 mW, 1% tolerance).
  • Purpose: Drops a tiny, predictable voltage to ensure both 3.3V power rails supply current equally rather than one dominating the load.
• D1 & D2 — Schottky Barrier Diodes (SOD-123 SMD):
  • Part Number: Diodes Inc. 1N5819HWQ-7-F (1A, 40V, low forward voltage).
  • Purpose: Allows current to flow into the LCD backlight while strictly preventing current from back-feeding from one 3.3V rail into the other (e.g., if one device is powered off or unplugged).

B. Display Decoupling Capacitors

When the display switches pixels or refreshes lines, sudden current surges can cause supply noise:

• C1 — 10 µF Bulk Ceramic Capacitor (0603 SMD):
  • Part Number: Fenghua 0603X106K100NT (10V, X5R dielectric).
  • Purpose: Stores local electrical charge and dampens low-frequency voltage dips.
• C2 — 100 nF High-Frequency Decoupling Capacitor (0603 SMD):
  • Part Number: Walsin 0603B104J500CT (50V, X7R dielectric).
  • Purpose: Filters out sharp, high-frequency switching noise right at the display power pin.

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3. High-Speed Bus Pinout (Pi Pico <-> FT232H)

All FT245 synchronous bus signals operate at 3.3V LVCMOS logic levels and run directly between the two chips:

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4. ILI9341 SPI Pinout

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5. Physical Assembly Notes

• Two-Sided Assembly:
  • Top side: FT232H module sockets (J_FT_L, J_FT_R), ILI9341 socket (J_LCD), SMD diodes (D1, D2), SMD resistors (R1, R2), and SMD capacitors (C1, C2).
  • Bottom side: Pi Pico socket headers (J_PICO_L, J_PICO_R).
• Standard Pitch: All headers are standard 2.54 mm (0.1") pitch vertical female socket headers.

Refrences:- AN130 AN135 AN165 AN167 AN124