ZHCS266F June 2011 – May 2017 TRF7960A
PRODUCTION DATA.
Table 6-36 describes the bit fields of the RSSI Levels and Oscillator Status register. This register reports the signal strength on both reception channels and RF amplitude during RF off conditions. The RSSI values are valid from reception start until the start of the next transmission.
RSSI measurement block is measuring the demodulated envelope signal (except in case of direct command for RF amplitude measurement described later in direct commands section). The measuring system is latching the peak value, so the RSSI level can be read after the end of receive packet. The RSSI value is reset during next transmit action of the reader, so the new tag response level can be measured. Section 6.7.1.1 and Section 6.7.1.2 describe the RSSI levels calculated to RF_IN1 and RF_IN2. The RSSI has 7 steps (3 bits) with 4-dB increment. The input level is the peak to peak modulation level of RF signal measured on one side envelope (positive or negative).
| BIT NO. | BIT NAME | FUNCTION | DESCRIPTION |
|---|---|---|---|
| B7 | Unused | ||
| B6 | osc_ok | Crystal oscillator stable indicator | 13.56-MHz frequency stable (approximately 200 µs) |
| B5 | rssi_x2 | MSB RSSI value of auxiliary RX (RX_IN2) | Auxiliary channel is by default RX_IN2. The input can be swapped by B3 = 1 (Chip State Control register). If "swapped", the auxiliary channel is connected to RX_IN1 and the auxiliary RSSI represents the signal level at RX_IN1. |
| B4 | rssi_x1 | Auxiliary channel RSSI | |
| B3 | rssi_x0 | MSB RSSI value of auxiliary RX (RX_IN2) | |
| B2 | rssi_2 | MSB RSSI value of Main RX (RX_IN1) | Active channel is the default and can be set with option bit B3 = 0 of the Chip Status Control register (0x00). |
| B1 | rssi_1 | Main channel RSSI | |
| B0 | rssi_0 | LSB RSSI value of Main RX (RX_IN1) |