Microchip Technology SA5 Series, User Manual

Page: 21 / 63

MAC-SA5X USER’S GUIDE
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2019 Microchip Technology Inc. DS50002938A-page 21
Chapter 3. Operation
This section will cover the following topics:
• Configure the Serial Port
• Analog Tuning
• Digital Frequency Adjustment
• Configure 1PPS Discipline Settings
• Query the MAC’s Health/Lock/Alarm Status
• Configure the Time of Day
3.1 CONFIGURE THE SERIAL PORT
The default settings for the RS-232 interface are listed below.
• Speed: 57600
bps
• Data Bits: 8 bits
• Parity: None
• Stop Bits: 1
• Flow Control: None
The baud rate can be configured via the bootstrap loader (BSL). The following
sequence illustrates how to query and set the baud rate. The following interaction
sequence begins with the SA5X unit already powered on:
TABLE 3-1: BOOTSTRAP LOADER INTERACTION SEQUENCE
Serial Communication Description
{reset}
User resets the CPU to access the bootloader.
[>Loading...]
After reset, BSL announces it is ready (waits 3 seconds).
{bsl}
User requests the BSL command mode (within 3 seconds).
[=BSL]
BSL confirms it is now in command mode.
{baud?}
User queries the currently configured baud rate (optional).
[=57600] <CR><LF>
BSL returns the configured baud rate.
{baud,921600,now}
User requests a new baud rate to take effect immediately.
Omission of “,now” argument will defer the change until the
next reset.
[=921600]
BSL confirms the newly configured baud rate.
{reset}
User resets the CPU for the new rate to take effect.
[>Loading...]
After reset, BSL announces its presence at 921600 bps.
See Chapter 4. “Command Line Interface” for reference on proper command syntax.
3.2 ANALOG TUNING
Analog tuning allows a user to correct the RF and 1PPS output frequency by applying
a DC correction voltage. Analog tuning is an inferior approach compared to Digital tun-
ing or 1PPS Disciplining because its resolution is only parts in 10
11
. However, it has
been carried forward to support legacy applications.