Z32AN00NW200SG Zilog, Z32AN00NW200SG Datasheet - Page 138

• Manufacturer Part Number: Z32AN00NW200SG
• Description: IC ARM922T MCU 200MHZ 256-BGA
• Manufacturer: Zilog
• Series: Encore!® 32r

Specifications of Z32AN00NW200SG

• Core Processor: ARM9
• Core Size: 16/32-Bit
• Speed: 200MHz
• Connectivity: EBI/EMI, IrDA, SmartCard, SPI, UART/USART, USB OTG
• Peripherals: DMA, LCD, Magnetic Card Reader, POR, PWM, WDT
• Number Of I /o: 76
• Program Memory Type: ROMless
• Ram Size: 64K x 8
• Voltage - Supply (vcc/vdd): 1.71 V ~ 3.6 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 256-LBGA
• For Use With: 269-4713 - KIT DEV ENCORE 32 SERIES
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Other names: 269-4717

Z32AN Series Data Sheet
16.3.3 UART Mode
16.3.4 Reading the Timer Count Values
DS0200-003
In UART mode, RxD of UART0, UART1, and UART2 are connected to timer inputs 4,5,6. Timer mode 7
(111b) can be used to measure the ASCII CR character 0x0D (13). The timer should be enabled to begin
searching for an auto baud character. The timer enable bit will clear once an auto baud character has been
measured.
To measure the auto baud character, the timer reload register should be setup with the maximum character
time. This allows the timer to automatically reject break conditions which can be used to reset the serial
interface. The timer measures the duration of 8 bit times. It starts measuring at the rising edge ending the
start bit to the rising edge beginning the stop bit.
To obtain the baud rate, the timer count should be divided by 8 (shifted right by 3) to get the individual bit
time. The bit count then needs to be divided by 16 (shifted right by 4) to obtain the baud rate. Rounding
should be done to achieve maximum resolution. Since the timer is preset to 1, the resulting character count
is one larger than the actual character time. The baud rate can be calculated as follows:
Since the auto baud timer automatically rejects baud rates too slow, a break condition can be used as a way
to reset the serial line. When software detects a break condition, it can place the timer in auto baud mode.
The auto baud search hardware will wait until the RxD pin is idle (high) before beginning an auto baud
measurement. Once the auto baud hardware sees the RxD pin go low for the start bit, it starts the counter. If
the timer overflows, it assumes a break condition was detected and will reset. The timer will wait for the RxD
pin to go high again before searching for another start bit character.
When the auto baud timer sees the rising edge at the end of the start bit, it will reset the timer and begin the
character measurement. It will stop counting once it sees the beginning of the stop bit which is two rising
edges of the RxD line later. If the counter overflows during this time, it automatically resets and waits for the
RxD line to go idle again before searching for another start bit character. If the counter does not overflow,
the timer enable bit will clear indicating an auto baud character was measured successfully. Figure 16-2
contains an illustration on auto baud timing.
The current count value in the timers can be read while the timer is counting (TEN = “1”). The read has no
effect on timer operation.
Figure 16-2: Auto baud Timing Diagram
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