EM357-RTR datasheet(56/241 Pages) SILABS

56 / 241 page

Rev 1.3

Two of the four external interrupts, IRQA and IRQB, have fixed pin assignments. The other two external interrupts,

IRQC and IRQD, can use any GPIO pin. The GPIO_IRQCSEL and GPIO_IRQDSEL registers specify the GPIO

pins assigned to IRQC and IRQD, respectively. Table 7.4 shows how the GPIO_IRQCSEL and GPIO_IRQDSEL

In some cases, it may be useful to assign IRQC or IRQD to an input also in use by a peripheral, for example to

generate an interrupt from the slave select signal (nSSEL) in an SPI slave mode interface.

Refer to "11. Interrupt System" on page 190 for further information regarding the EM35x interrupt system.

7.9. Debug Control and Status

Two GPIO registers are largely concerned with debugger functions. GPIO_DBGCFG can disable debugger

operation, but has other miscellaneous control bits as well. GPIO_DBGSTAT, a read-only register, returns status

related to debugger activity (GPIO_FORCEDBG and GPIO_SWEN), as well a flag (GPIO_BOOTMODE) indicating

whether nBOOTMODE was asserted at the last power-on or nRESET-based reset.

Table 7.4. IRQC/D GPIO Selection

GPIO_IRQxSEL

GPIO

GPIO_IRQxSEL

GPIO

GPIO_IRQxSEL

GPIO

PA0

PB0

PC0

PA1

PB1

PC1

PA2

PB2

PC2

PA3

PB3

PC3

PA4

PB4

PC4

PA5

PB5

PC5

PA6

PB6

PC6

PA7

PB7

PC7

EM357-RTR Datasheet(PDF) 56 Page - Silicon Laboratories

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