数码管进行两位计数。此芯片有掉电保护功能，当板子断电后，数码管计数仍然保持在断电前的数字，接上电源后，继续前面的状态进行计数。-Digital tube two count. This chip has a power-down protection, when the board is powered down, the digital count remains at the front of the digital power after the power is on, in front