1. Ingenic JZ47xx SoCs Timer/Counter Unit hardware¶

The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a multi-functionhardware block. It features up to eight channels, that can be used ascounters, timers, or PWM.

• JZ4725B, JZ4750, JZ4755 only have six TCU channels. The other SoCs allhave eight channels.

• JZ4725B introduced a separate channel, called Operating System Timer(OST). It is a 32-bit programmable timer. On JZ4760B and above, it is64-bit.

• Each one of the TCU channels has its own clock, which can be reparented to threedifferent clocks (pclk, ext, rtc), gated, and reclocked, through their TCSR register.

  • The watchdog and OST hardware blocks also feature a TCSR register with the sameformat in their register space.
  • The TCU registers used to gate/ungate can also gate/ungate the watchdog andOST clocks.

• Each TCU channel works in one of two modes:

  • mode TCU1: channels cannot work in sleep mode, but are easier tooperate.
  • mode TCU2: channels can work in sleep mode, but the operation is a bitmore complicated than with TCU1 channels.

• The mode of each TCU channel depends on the SoC used:

  • On the oldest SoCs (up to JZ4740), all of the eight channels operate inTCU1 mode.
  • On JZ4725B, channel 5 operates as TCU2, the others operate as TCU1.
  • On newest SoCs (JZ4750 and above), channels 1-2 operate as TCU2, theothers operate as TCU1.

• Each channel can generate an interrupt. Some channels share an interruptline, some don’t, and this changes between SoC versions:

  • on older SoCs (JZ4740 and below), channel 0 and channel 1 have theirown interrupt line; channels 2-7 share the last interrupt line.
  • On JZ4725B, channel 0 has its own interrupt; channels 1-5 share oneinterrupt line; the OST uses the last interrupt line.
  • on newer SoCs (JZ4750 and above), channel 5 has its own interrupt;channels 0-4 and (if eight channels) 6-7 all share one interrupt line;the OST uses the last interrupt line.