Source code for jitxexamples.jumpstart_kits.js2_circuits.straps
"""Strap-in configuration of the KSZ9031RNX.
Transcribed from Table 2-2 ("Strap-In Options - KSZ9031RNX") of data sheet
DS00002117K. Each strap-in function is latched from the level on its pin at
power-up or reset: a pull-up latches 1, a pull-down latches 0. The strap pins
have no internal pull (Table 2-1 types them I/O, and Table 6-6 lists internal
pull-ups only on MDC, MDIO and RESET_N), so every strap pin takes an external
resistor for every configuration.
====== ========== ================== =======================================
Pin Pin name Strap function Value
====== ========== ================== =======================================
35 RX_CLK PHYAD2 PHY address bit 2
15 LED2 PHYAD1 PHY address bit 1
17 LED1 PHYAD0 PHY address bit 0
27 RXD3 MODE3 ``Mode`` code bit 3
28 RXD2 MODE2 ``Mode`` code bit 2
31 RXD1 MODE1 ``Mode`` code bit 1
32 RXD0 MODE0 ``Mode`` code bit 0
33 RX_DV CLK125_EN 1 enables the 125 MHz CLK125_NDO output
41 CLK125_NDO LED_MODE 1 is single-LED, 0 tri-color dual-LED
====== ========== ================== =======================================
"""
from dataclasses import dataclass
from enum import Enum
[docs]
class Strap(Enum):
"""A strap-in function of Table 2-2, valued by the pin number carrying it."""
PHYAD2 = 35
PHYAD1 = 15
PHYAD0 = 17
MODE3 = 27
MODE2 = 28
MODE1 = 31
MODE0 = 32
CLK125_EN = 33
LED_MODE = 41
[docs]
class Mode(Enum):
"""The MODE[3:0] codes Table 2-2 defines, valued by the 4-bit code.
The codes it marks "Reserved - not used" (0000 to 0011, 0101, 0110, 1000 to
1011) have no member, so ``Mode(0b0101)`` raises ``ValueError``.
"""
NAND_TREE = 0b0100
CHIP_POWER_DOWN = 0b0111
RGMII_1000_FULL = 0b1100
"""RGMII, advertise 1000BASE-T full-duplex only."""
RGMII_1000_FULL_HALF = 0b1101
"""RGMII, advertise 1000BASE-T full- and half-duplex only."""
RGMII_ALL_EXCEPT_1000_HALF = 0b1110
"""RGMII, advertise 10/100/1000 half- and full-duplex except 1000BASE-T
half-duplex."""
RGMII_ALL = 0b1111
"""RGMII, advertise 10/100/1000 half- and full-duplex."""
[docs]
class LedMode(Enum):
"""LED_MODE, valued by the latched bit."""
TRI_COLOR_DUAL = 0
SINGLE = 1
[docs]
@dataclass(frozen=True)
class StrapConfig:
"""The configuration the strap resistors latch.
Args:
phy_address: PHYAD[2:0], 0 to 7. Address bits [4:3] are always 00.
mode: MODE[3:0].
clk125_output: CLK125_EN, whether CLK125_NDO drives a 125 MHz clock.
led_mode: LED_MODE.
Raises:
ValueError: ``phy_address`` is outside 0 to 7.
"""
phy_address: int = 0
mode: Mode = Mode.RGMII_ALL
clk125_output: bool = False
led_mode: LedMode = LedMode.SINGLE
def __post_init__(self) -> None:
if not 0 <= self.phy_address <= 7:
raise ValueError(
f"KSZ9031RNX PHY address {self.phy_address} is outside 0 to 7: "
"PHYAD[2:0] sets three bits"
)
if not isinstance(self.mode, Mode):
raise TypeError(f"mode must be a Mode, not {self.mode!r}")
if not isinstance(self.led_mode, LedMode):
raise TypeError(f"led_mode must be a LedMode, not {self.led_mode!r}")
[docs]
def level(self, strap: Strap) -> bool:
"""The level ``strap`` latches: True for a pull-up, False for a pull-down."""
match strap:
case Strap.PHYAD2:
return bool(self.phy_address & 0b100)
case Strap.PHYAD1:
return bool(self.phy_address & 0b010)
case Strap.PHYAD0:
return bool(self.phy_address & 0b001)
case Strap.MODE3:
return bool(self.mode.value & 0b1000)
case Strap.MODE2:
return bool(self.mode.value & 0b0100)
case Strap.MODE1:
return bool(self.mode.value & 0b0010)
case Strap.MODE0:
return bool(self.mode.value & 0b0001)
case Strap.CLK125_EN:
return self.clk125_output
case Strap.LED_MODE:
return self.led_mode is LedMode.SINGLE
DEFAULT_STRAPS = StrapConfig()
"""PHY address 0, every RGMII mode advertised, CLK125_NDO off, single-LED mode."""
