TMP92CZ26A
92CZ26A-43
3.4 Boot ROM
The TMP92CZ26A contains boot ROM for downloading a user program, and supports two
kinds of downloading methods.
3.4.1 Operation Modes
The TMP92CZ26A has two operation modes: MULTI mode and BOOT mode. The
operation mode is selected according to the AM1 and AM0 pin levels when
RESET is
asserted.
(1) MULTI mode: After reset, the CPU fetches instructions from external memory and
executes them.
(2) BOOT mode: After reset, the CPU fetches instructions from internal boot ROM
and executes them. The boot ROM loads a user program into internal
RAM from USB, or via UART, and then branches to the internal
RAM. In this way the user program starts boot operation.
Table 3.4.2
shows an outline of boot operation.
Table 3.4.1 Operation Modes
Mode Setting Pins
RESET
AM1 AM0
Operation Mode
0 1 MULTI Start from external 16-bit bus memory
1 0 TEST (Setting prohibited)
1 1 BOOT (Start from internal boot ROM)
0 0 TEST (Setting prohibited)
Table 3.4.2 Outline of Boot Operation
Loading
Name Priority
Source I/F Destination
Operation after
Loading
(a) 1 PC (UART) UART
(b) 2 PC (USB_HOST) USB
Internal RAM
Branch to internal
RAM
