CHAPTER 1: System Overview
36 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
3. Mode
This section explains the function of operating modes.
In this family, the following operating modes can be used:
− User Mode
Internal ROM (Flash memory) Startup: CPU obtains a reset vector from Flash memory and starts
operations.
− Serial Writer Mode
Serial write to Flash memory is enabled.
*: For the details of this mode, see Flash Programming Manual of the product used.
Operating modes are determined after a release of respective power-on reset, low voltage detection reset,
and INITX pin input reset.
*: For the details of power consumption control and clock selection modes, see other chapters Low Power
Consumption Mode and Clock.
How to Set Operating Mode
Operating modes are configured by MD pins’ (MD1 and MD0) inputs.
User Mode Internal ROM(Flash memory) Startup
Startup Sequence
Processes to determine operating modes in the startup sequence are shown below:
1. MD Pin Sampling
2. Determining Operating Mode and Retaining Mode Data
The descriptions of these processes are as follows:
1. MD Pin Sampling
Operating mode is configured by MD pin inputs (MD1, MD0). These inputs are sampled by
power-on reset, low-voltage detection reset, and INITX pin input reset.
Until each reset, which is the sampling factor, is released, MD1 and MD0 pin inputs need to be
determined.
2. Determining Operating Mode and Retaining Mode Data
MD1 and MD0 which are sampled by respective resets are retained until respective resets are
input again.
Operating modes are determined by the retained MD1 and MD0. Therefore, even MD1 and MD0
are changed after a reset is released, it does not affect an operating mode.
MD1 pin
MD1 pin is used also as GPIO. This pin can be continually used as GPIO after setting a mode.
To Next Page
Loading...
