Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual AT Command Macros Customized AT Commands

AN93

The commands end with a <CR>, which, in combination with the final<CR>, provides the <CR><CR> delimiter. Boot commands must be the first entry in the EEPROM and are used to set the modem up with custom defaults, such as settings for specific countries, auto answer, or other special settings upon power up or after a hardware or software reset.

This saves the host processor from reloading special configuration strings at power up or after a reset, and allows the modem to be customized by programming the EEPROM or by substituting preprogrammed EEPROMs. If the BOOT command is the final entry in the EEPROM, it must end with an additional <CR> to provide the <CR><CR><CR> delimiter indicating the end of the EEPROM.

2.6.5. AT Command Macros (Customized AT Commands)

Macros allow the creation of single custom AT commands that execute combinations of default AT commands including special register configurations. AT command macros have the following format:

<command name><CR> <commands><CR> <commands><CR> <CR>

Each AT Command Macro ends with a <CR><CR>. The final entry in the EEPROM ends with an additional <CR> to provide the <CR><CR><CR> delimiter indicating the end of the EEPROM. AT command macros can have a name consisting of any string of characters but must be the only command on a line.

2.6.6. Firmware Upgrades

Firmware upgrades (“patches”) are typically executed upon boot-up and stored between the heading, BOOT, and the first <CR><CR> delimiter. A firmware upgrade has the format: BOOT<firmware upgrade><CR>. The firmware upgrade ends with a <CR>, which, in combination with the final<CR>, provides the <CR><CR> delimiter, which marks the end of the EEPROM contents. A firmware upgrade can also be stored as an AT command macro in a system where using the firmware upgrade is optional. The following are examples of boot commands, AT command macros, and automatically-loaded firmware upgrades.

2.6.6.1. Boot Command Example

On power-up or reset, it is desired to set the UART rate to 115.2 kbps and limit the ISOmodem to V.34 and lower operation.

The AT commands required to do this manually are:

AT\T12<CR>

AT&H2<CR>

To implement this as a boot command, the commands are:

BOOT<CR>

AT\T12<CR>

AT&H2<CR>

<CR>

This must be written to the EEPROM as ASCII hexadecimal in eight address blocks. The actual AT commands to store this boot command in the EEPROM starting at address 0 are:

AT:M0000,42,4F,4F,54,0D,41,54,5C

AT:M0008,54,31,32,0D,41,54,26,48

AT:M0010,32,0D,0D,00,00,00

The value 0x41 corresponds to the display character A, 0x54 to T, 0x42 to B, 0x4F to O etc., and the value 0x0D, for carriage return corresponds to the decimal value, 13, stored in S-register 3 (S3). Table 30 shows the relationship between the decimal values, hexadecimal values, and display characters.

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