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AFE4420: AFE4420: FIFO outputs random data

Part Number: AFE4420

Hi, there

We configured AFE4420 to have 6 phases. An interrupt is generated every 1/120 second to output the data. Each phase is 355us in length and consists of turning on LED, ADC sampling and conversion, etc.

The detailed AFE4420 register configurations are as follows:

0x1D 0x00208D 0x00208E
0x23 0x001600 0x021600
0x42 0x000160 0x000160
0x6C 0x200000 0x200000
0x78 0x000007 0x00000D
0x88 0x000005 0x000005
0x8A 0x1330CC 0x1330CC
0x8B 0x0F0F03 0x0F0F03
0x8D 0x010004 0x010004
0x8E 0x008003 0x008003
0x8F 0x000003 0x000003
0xB8 0x020808 0x020808
0xB9 0x801C12 0x801C02
0xBA 0x001064 0x001064
0xBB 0x020202 0x020202
0xBC 0x801C12 0x081C02
0xBD 0x001064 0x001064
0xBE 0x020000 0x020000
0xBF 0x801C02 0x801C02
0xC0 0x001064 0x001064
0xC1 0x020101 0x020101
0xC2 0x801C12 0x801C12
0xC3 0x001064 0x001064
0xC4 0x010404 0x010404
0xC5 0x801C12 0x801C12
0xC6 0x001064 0x001064
0xC7 0x010000 0x010000
0xC8 0x801C02 0x801C02
0xC9 0x001064 0x001064

Register 0xAC and 0xAE are programmed dynamically depending on the AGC algorithm. Other registers are left untouched. 

The issue is that one of the phases, 2, 4 or 6, will give us negative maximum, i.e., 0xE00000, from the FIFO register 0xFF. It is always one phase that does this, and it seems to us that this happens randomly to one of the 2, 4 or 6 phases.

Can you take a look at the register configurations and let us know what we did wrong ?

Let us know if you need more information.

Thank you.