TSA5511 PLL Controller for Arduino

Project overview

This project provides a compact Arduino-based front-panel controller for TSA5511 PLL designs. It brings persistent configuration, everyday operating functions and service diagnostics to a 16x2 LCD interface, so frequency control, memory handling, RF-drive control and maintenance checks can be handled directly from the hardware.

The controller is intended for VCO frequency control from 64 MHz up to 1,300 MHz, within the specification range of the TSA5511. It supports configurable VCO bands, selectable PLL crystal frequency, I²C address handling, periodic TSA5511 status monitoring, live lock/input diagnostics, PLL lock-time measurement, PLL divisor display, current I²C address, POR and I²C recovery counters, system uptime, output-port diagnostics, state-aware recovery from communication loss or unexpected PLL resets, user memories, station-name editing, temporary RF-drive control, optional menu-title display and LCD backlight control.

Main features

• ATmega328P-based 5 V Arduino Nano or fully compatible controller platform
• 16x2 LCD user interface in 4-bit mode
• Three-button operation using DOWN, SET and UP
• Consistent SET-button gesture handling for confirmation, return and cancellation
• Double-click access to the System Menu
• Long-press access to the Quick Menu
• Hidden Service Menu opened by holding UP and DOWN together for one second, including during runtime I²C recovery, or during startup by holding SET through the splash screen
• Read-only diagnostics with live TSA5511 status, lock timing, PLL divisor, input bits, output-port bitmap, current I²C address, POR/recovery counters and system uptime
• Service-menu System Info with full firmware version
• Named VCO bands: FM OIRT, FM Japan, FM World, 2 m, 70 cm, UHF and 64-1300 MHz
• Frequency precision matched to exactly representable PLL/display step sizes
• Separate last-frequency memory per VCO band and crystal setting
• Six exact user memory slots per VCO band and crystal setting, with automatic precision increase on recall when required
• Selectable TSA5511 I²C address with verification when saving changes
• Configurable PLL crystal frequency: 1.6 MHz or 3.2 MHz
• Selectable high/low charge-pump current and varicap-drive disable
• Output port mapping for lock, unlock and RF-stage control
• Station-name editor for the idle display
• Temporary RF-drive enable/disable control without EEPROM storage
• Optional LCD backlight dimming and smooth manual backlight fade-out
• Optional animated menu title display for System, Quick and Service menus
• Double-confirmed factory reset in the Service Menu, with a dedicated resetting status shown for at least 750 ms while defaults are restored
• Transactional System Menu editing: changes remain temporary until SAVE CHANGES; discard/timeout leaves the active PLL settings untouched
• Explicit SET to edit prompts for system settings and a * marker on EXIT MENU when unsaved changes are pending
• Adaptive System Menu exit: return directly when unchanged, otherwise offer save/discard/cancel
• Startup Service Menu with read-only pre-initialization diagnostics and a single-confirmation I²C fallback option that restores the fail-safe address 0x61
• State-aware I²C recovery that preserves PLL programming after read-only interruptions and reprograms after uncertain writes or POR
• Service Menu and Diagnostics remain browsable during I²C recovery, with a fixed ! marker on every page while SYSTEM UPTIME continues to refresh; unavailable FL/input values shown as -, actively driven input ports masked as -/---, and interrupted lock timing shown as <unknown>

Hardware overview

The hardware consists of an ATmega328P-based 5 V Arduino Nano or a fully compatible board, a standard 16x2 LCD, three pushbuttons with 470 nF debounce capacitors, the TSA5511 PLL circuit and an optional PLL lock LED. The lock LED can also act as a blinking fault indicator, while the LCD displays the lock status directly.

Pull-up resistors on SDA and SCL are required. If the I²C bus passes through RF-decoupling circuitry, lower values may improve communication reliability; the supplied wiring diagram shows 2.2 kΩ. When using TSA5511 package variants with fewer available output ports, make sure that port mapping only selects physically available ports.

Operation and settings

• System Menu: double-click SET to configure VCO, PLL and general settings. Settings show SET to edit while browsing; EXIT MENU carries a * when unsaved changes are pending and otherwise returns directly when nothing changed.
• VCO settings: select FM OIRT, FM Japan, FM World, 2 m, 70 cm, UHF or 64-1300 MHz and choose the displayed/settable frequency precision.
• PLL settings: configure the I²C address, PLL crystal frequency, charge-pump current or varicap-drive disable mode, and output-port mapping. When saving changes after selecting a new I²C address, communication is automatically verified.
• General settings: edit the station name shown in the idle locked state, configure LCD backlight dimming and toggle the animated menu-title display. In the station-name editor, short SET confirms a character and holding SET returns from the editor.
• Quick Menu: press and hold SET to recall, save or clear user memories, temporarily toggle RF drive, turn off the LCD backlight, or select EXIT MENU.
• Service Menu: hold UP and DOWN together for one second from the main interface, or hold SET through the startup splash screen to enter it before normal PLL initialization. It provides DIAGNOSTICS, SYSTEM INFO, FACTORY RESET and EXIT MENU; startup entry additionally exposes I2C FALLBACK to restore address 0x61 after a single NO/YES confirmation. An already active startup I²C fault keeps its ! marker and blinking fault indicator throughout the fallback display until communication is subsequently verified. Read-only I²C probing remains active throughout the startup Service Menu; live TSA5511 values remain - until the first valid status read. Failed reads mark every startup Service Menu screen with ! and blink the fault indicator immediately until communication returns, while sustained failures replace stale live FL/input values with -. During normal operation, INPUTS masks actively driven P7/P5/P4 outputs as - and an actively driven P6 as ---; high-impedance ports show their external input levels. Startup Service Menu intentionally keeps the raw status values because the previous TSA5511 output-port state may be unknown.

In normal use, the VCO frequency is adjusted with UP and DOWN and confirmed with a short SET press. A brief chord-acquisition window allows the UP+DOWN Service Menu gesture to be recognized without briefly entering frequency edit mode, and the same gesture remains available during runtime I²C recovery. Holding SET cancels a pending frequency change, while holding UP or DOWN starts an accelerated sweep. A chord that begins during frequency editing is consumed until both buttons are released, so it cannot open the Service Menu after the edit times out. The System Menu discards unsaved changes on timeout; during normal operation the Service Menu and DIAGNOSTICS use a longer timeout, while startup Service Menu/DIAGNOSTICS do not time out and resume initialization only after explicit exit. Quick Menu actions are applied immediately. After LCD wake-up, the waking press is consumed until all buttons have been released. PLL lock is verified after programming. To prevent false unlock indications caused by FM modulation, operational lock-flag polling stops after lock has been detected, while periodic TSA5511 status monitoring remains active. DIAGNOSTICS refreshes raw status information without overriding operational lock state or output-port control. It also exposes PLL divisor, current I²C address, recovery count and controller uptime. Before PLL initialization, the first valid status read establishes the expected POR baseline; lock timing, PLL divisor and output-port command data are marked as not initialized, and the output-port command remains so until the first successful PLL programming. During runtime I²C recovery, both the Service Menu and DIAGNOSTICS remain browsable; every page carries a fixed ! in the upper-right. SYSTEM UPTIME continues to refresh, unavailable FL/input values are shown as - and interrupted lock timing is shown as <unknown>. A read-only interruption invalidates the measured lock time until a new uninterrupted acquisition starts. The recovery counter is incremented only after recovery has successfully completed. After a completed I²C recovery, the LCD controller is reinitialized before the interface is redrawn, helping resynchronize the display if the fault or a related supply disturbance affected its controller state. Existing PLL programming is retained after a read-only interruption without POR; full reprogramming is performed only after an uncertain write or an unexpected TSA5511 reset indicated by POR.

Source code and documentation

The complete Arduino sketch and project documentation are available in the public GitHub repository. Use the repository for the latest source code, detailed comments, pin mappings and version history.

Open the GitHub repository