AN3123 Datasheet, PDF (6/30 Pages) STMicroelectronics – Using the UART interfaces in the SPEAr embedded MPU family

UART signals
AN3123
In SPEAr300, the device offers several different PL_GPIO sharing modes. Different
blocks/IPs are available in different configuration modes.
This has an effect on the above mentioned UART signals also. Not all SPEAR300 UART
signals in Table 3 are available in all configurations.
This is because for many applications UART is used in NULL modem mode and only
UART_RX & UART_TX are sufficient.
There are 13 possible UART configurations in SPEAr300 which can be selected by RAS
control register 2.
In configuration 1 & configuration 2, the UART with modem control lines is available.
In configurations 3 to 13, the UART without modem control lines is available (see Table 6).
Table 5. UART configurations for SPEAr300
Signal
Configuration 1 Configuration 2
PL_GPIO[42]
UART_DTR
UART_DTR
PL_GPIO[41]
UART_RI
UART_RI
PL_GPIO[40]
UART_DSR
UART_DSR
PL_GPIO[39]
UART_DCD
UART_DCD
PL_GPIO[38]
UART_CTS
UART_CTS
PL_GPIO[37]
UART_RTS
UART_RTS
PL_GPIO[3]
UART_RX
UART_RX
PL_GPIO[2]
UART_TX
UART_TX
Configurations 3 to 13
-
-
-
-
-
-
UART_RX
UART_TX
Note:
On PL_GPIO[3] and PL_GPIO[2] UART_RX and UART_TX are multiplexed with external
memory controller (FSMC) signals /E3 and /E4 respectively.
2.3
SPEAr310
In SPEAr310 the external pin connections of UART1 are the same as in SPEAr300.
You can configure the device to have either
● up to 6 UARTs without modem control lines or
● 1 UART with modem control lines.
Refer to Table 3.
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Doc ID 16862 Rev 2