7.2 Enabling Interrupts
It is important to remark that the previous two function enable/disable an interrupt at the
NVIC controller level. Looking a Figure 1, you can see that an interrupt line is asserted by the
peripheral connected to that line. For example, the USART2 peripheral asserts the interrupt line
that corresponds to the USART2_IRQn interrupt line inside the NVIC controller.
There is no USART2 in Figure 1, is this an error and do you have an errata page where errors in the book are being fixed and updated.