Data Sheet

ISM4343 Specification
DOC-DS-20074-5.3
Inventek Systems
Page 12
6.1 UART Interface
The ISM4343-WBM-L151 shares a single UART for BT. The UART is a standard 4-wire
interface (RX, TX, RTS and CTS) with adjustable baud rates from 9600 baud to 4.0
Megabaud. The interface features an automatic baud rate detection capability that
returns a baud rate selection. Alternatively, the baud rate may be selected through a
vendor-specific UART HCI command.
The UART has a 1040-byte receive FIFO and a 1040-byte transmit FIFO to support EDR.
Access to the FIFO is conducted through the AHB interface through either DMA or the
CPU. The UART supports the BT 4.0 UART HCI specification: H4, a custom Extended
H4 and H5. The default baud rate is 115.2 Kbaud.
The UART supports the 3-wire H5 UART transport, as described in the BT specification
(“Three-wire UART Transport Layer”). Compared to H4, the H5 UART transport reduces
the number of signal lines required by eliminating the CTS and RTS signals.
The ISM4343-WBM-L151 UARTs operate correctly with the host UART as long as the
combined baud rate error of the two devices is within ±2%.
Desired Rate
Actual Rate
Error (%)
921600
923077
0.16
460800
461538
0.16
230400
230796
0.17
115200
115385
0.16
57600
57692
0.16
38400
38400
0.00
28800
28846
0.16
19200
19200
0.00
14400
14423
0.16
9600
9600
0.00
Table 1: Example of Common Baud Rates
6.2 UART Pins
The eS-WiFi module and SiP support a 3.3v logic level, UART host interface when
using the IWIN AT Command Firmware or WICED SDK.
UART Pins to connect when using the ISM4343-WBM-L151 SiP:
Pin
Description
STM32F412
31
USART1_RX
PA10
30
USART1_TX
PA9