How many interrupt priority levels does the H8S/21xx Interrupt Controller have?
The H8S/21xx interrupt controller can be operated in one of two modes. In mode 0 all interrupts have the same priority, except for vector address priority. If an interrupt is enabled, it will be excepted if the I bit in the CCR is cleared to 0. If the Ibit is set to 1, all interrupts will be held pending until the I bit is cleared to 0. If more than 1 interrupt has been held pending, the interrupts are serviced in the order set by their respective vector address. Interrupts with a lower vector addresshave higher priority. In mode 1, interrupts can have a priority of either 1 or 0 associated to them. This priority level is set in the Interrupt Control Registers A to C. If both the I & UI bits are cleared to 0, then all interrupts are serviced.If the I bit in the CCR is set to 1, then interrupts with a priority of 0 will be held pending. Interrupts with a priority of 1 will be serviced. If both the I & UI bits in the CCR are set to 1, then all interrupts are held pending.
|H8S/2258, 2239, 2238, 2237, 2227|