COP8AME9_14 Datasheet, PDF (58/102 Pages) Texas Instruments – COP8AME9 8-Bit CMOS Flash Microcontroller with 8k Memory, Dual Op Amps, Virtual EEPROM, Temperature Sensor, 10-Bit A/D and Brownout Reset

COP8AME9, COP8ANE9
SNOS930F – MARCH 2001 – REVISED MARCH 2013
www.ti.com
DIAGNOSTIC
Bits CHL0 and CHL1 in the ENU register provide a loopback feature for diagnostic testing of the USART. When
both bits are set to one, the following occurs: The receiver input pin (RDX) is internally connected to the
transmitter output pin (TDX); the output of the Transmitter Shift Register is “looped back” into the Receive Shift
Register input. In this mode, data that is transmitted is immediately received. This feature allows the processor to
verify the transmit and receive data paths of the USART.
Note that the framing format for this mode is the nine bit format; one Start bit, nine data bits, and one or two Stop
bits. Parity is not generated or verified in this mode.
ATTENTION MODE
The USART Receiver section supports an alternate mode of operation, referred to as ATTENTION Mode. This
mode of operation is selected by the ATTN bit in the ENUR register. The data format for transmission must also
be selected as having nine Data bits and either one or two Stop bits.
The ATTENTION mode of operation is intended for use in networking the device with other processors. Typically
in such environments the messages consists of device addresses, indicating which of several destinations should
receive them, and the actual data. This Mode supports a scheme in which addresses are flagged by having the
ninth bit of the data field set to a 1. If the ninth bit is reset to a zero the byte is a Data byte.
While in ATTENTION mode, the USART monitors the communication flow, but ignores all characters until an
address character is received. Upon receiving an address character, the USART signals that the character is
ready by setting the RBFL flag, which in turn interrupts the processor if USART Receiver interrupts are enabled.
The ATTN bit is also cleared automatically at this point, so that data characters as well as address characters
are recognized. Software examines the contents of the RBUF and responds by deciding either to accept the
subsequent data stream (by leaving the ATTN bit reset) or to wait until the next address character is seen (by
setting the ATTN bit again).
Operation of the USART Transmitter is not affected by selection of this Mode. The value of the ninth bit to be
transmitted is programmed by setting XBIT9 appropriately. The value of the ninth bit received is obtained by
reading RBIT9. Since this bit is located in ENUR register where the error flags reside, a bit operation on it will
reset the error flags.
BREAK GENERATION
To generate a line break, the user software should set the BRK bit in the ENUI register. This will force the TDX
pin to 0 and hold it there until the BRK bit is reset.
A/D Converter
This device contains a 7-channel, multiplexed input, successive approximation, 10-bit Analog-to-Digital Converter
with Programmable Gain Amplifier. One A/D channel is internally connected to the temperature sensor. The
remaining six channels are connected to pins B2-B7 and are available external to the device. Pins AV_CC and
AGND are used for the A/D Converter, Temperature Sensor, Programmable Gain Amplifier, and Stand-Alone
Amplifier.
OPERATING MODES
The simplified block diagram of the A/D Converter is shown in Figure 27.
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