Dear TI expert:
At present, when developing a new 3D printer, TM4C123X MUC is used as the main control chip, and some problems are encountered in the application process:
A. Pins 51 (PC1) and 52 (PC0) of the chip are used as common IO ports (PC0 and PC1 are TCK and TMS of JTAG). Due to insufficient chip resources, pins of JTAG are used as GPIO.
B. In the process of debugging, after the PC0 and PC1 repeatedly change state, a program is running the wrong case, show the other IO port output state is not correct, other input IO undetectable state changes, but PC0 and PC1 can detect port status changes, in this case the chip of USB communication available, PC can get the information of USB;
C. IO input adopts the query mode, and the timer is used to realize the cyclic timing query. USB adopts the method of interrupt receiving and sending after receiving the effective data.
D. The GPIOLOCK register has been set as 0X4C4F434B in the program, the GPIOCR register has been set, and the GPIO configuration program is the official routine of TI;
E. When setting system variables in the program, it can be seen that the program runs into functions that should not be called. It is not clear how to enter the system.
F. After PC0 and PC1 input a special timing sequence, the program can be restored to normal, and the status of other IO ports is normal, but it can be judged that the program is not reset and restarted, because USB can communicate all the time, and the communication has not been reconnected continuously;
G. If PC0 or PC1 is replaced with IO, the above phenomenon will not occur.
Please help to analyze the cause of the above situation,many thanks!!
